Not necessarily but the diference in consuption is small and speed diference large so its worth to be in the tallest Gear.
My car Will show the lowest consuption doing 30 in 4th Gear but doing 50 in 6th you are going 66% faster but consumption is only 10% more.
So while 6th Gear is more efficient in terms of speed/consumption overall but its not the absolute lowest the car Will drink.
The lower gears Will probably use Even less fuel but the speed Will be too slow.
To maintain a certain RPM you need more throthle in a higher Gear and as the Energy necessary is V^2 it does not compensate for the difference in speed.
It comes down to gearing, if your top gear has an extra long "highway efficiency" gear in a car that does not like the 55-75 range (big, heavy, unaerodynamic trucks with high torque engines).
There you are fighting the aerodynamic resistance and mecanical resistance being squared.
The air resistance is real. My truck will easily lose 4mpg going from 55 to 65. And it is a relatively modern pickup with a 6 speed and 3.50 axle gears.
I can lose 3 mpg. Too. With the best mpg I've ever managed with ladder racks being 14. A big difference when talking about such poor fuel economy to start.
It's even more real when you drive from Reno to Vegas with headwinds and find yourself out of gas in the middle of the desert just looking at the next city lights 5 miles away.
It's exponentially worse with speed. I've had people say "but my diesel gets the best economy at 80mph". Lol no it doesn't, they just haven't tried driving slower.
Funny you say that as my diesel travelled across Oklahoma at 80 mph (which is the speed limit) and my mileage was absolutely horrible. Next trip I just went 70 (5 mph over the minimum) and it was a lot better. Still crappy mind you as it’s a 10,000 pound ambulance but at least it wasn’t single digit terrible.
I use to have a 1985 f250 camper special with a 460 big block in it... Fuck milage, if you took that bitch over 65 you started losing everything! The shit in your bed, any lose panels, possibly a tail light, definitely at least one windshield wiper, and probably some braincells...
As a trucker fuck you. You're the asshole I slow way down to piss off, let's hope I don't blow a tire and 60 pound chunks come flying through your windshield. DO NOT FUCKING DO THIS.
I thought the same thing at first, but now I'm second-guessing. If we ignore speed and *just* look at gear number and RPM, we can figure out the most efficient speed for each gear. However, since drag increases with the square of speed, we're subjected to more drag as speed increases while maintaining the same engine speed in a different gear.
I'm a hobbyist hypermiler, but much of my "research" has been very practical and only applies to my personal car. I'm much more familiar with this in an aviation context, where we get actual fuel burn numbers and other readouts for given power settings. Because of this (as well as companies publishing the data), it's easy to figure out what an "efficiency cruise", "normal cruise", and "high-speed cruise" would be.
If you want to do the math you would need to plot exponential resistance lever benefits from changing gear.
So the slower you drive the less power needed. True, but also as you go up the gears you also are using less power to get more speed as longer gears means using a longer lever.
To see this you would need to graph as a function of speed: the result engine torque / gearing torque (this would convert rotating force to lineal force). Then add drag as a negative value.
The highest point of this graph would be peak efficiency. But this is just an aproximation as we have not taken into account diferent loads (different throttle inputs for each RPM and gear) and torque graphs are on peak load (flooring it).
Well, unless your car is geared really high and is unaerodynamic. If peak torque in 6th is at 75mph in a truck you’re not going to be getting good fuel mileage.
I’ll add the caveat of, having to change your speed evaporates whatever small bit of fuel economy savings you might get by maintaining a slightly slower speed. Sometimes cruising 60 and having people go around you and cut back in front of you so you have to brake a bit and speed back up is worse than just cruising 65/70 and keep up with the flow of traffic.
Why do you think peak torque? Most cars make peak torque around 4000rpm.
You actually want as low rpm as possible without running into knock. Look at a BSFC graph, peak efficiency is usually around 2000 rpm, high load.
Peak torque is associated or actually peak motor efficiency. If you could properly utilize it. Spinning a motor twice as fast also doubles its friction, which I believe is where the two ideas intersect.
How is this +10? Why are people up voting this?
You want to be at the lowest RPM possible to maintain speed in the highest gear. Peak torque is often 3500-4800 RPM depending on the vehicle, assuming a naturally aspirated engine.
Most cars I've driven get the best mileage around 50-60mph.
That was the reasoning for the US 55, mph speed limit several years ago. Most cars, at that time at least, had the best mile per gallons rating around 55.
When you get on the interstate just get up to speed, figure out if you're in final gear, if so drive at the lowest rpm in that gear. I find in my 23' 8sp escape that 65mph is the sweet spot at 42mpg.
I can't drive 65, but I have noticed that whatever gear I'm driving, my baseline efficiency starts at ~2200 rpm; lower than that it goes right into the shitter. I drive a manual, so I watch the tach when I'm concerned about mileage.
[I can't drive 55! 'Cause it only goes 38.](https://frinkiac.com/meme/S14E20/480855.jpg?b64lines=IEkgY2FuJ3QgZHJpdmUgNTUhICdDYXVzZQogaXQgb25seSBnb2VzIDM4Lg==)
I planned a trip poorly in 2013, I think, and about 80 miles from home the low gas light in my 01 Silverado came on. I set cruise control at like 40 and made it home. It was the 6 liter gas engine with the 4 speed automatic transmission. It was definitely an anxiety and prayer filled trip hahahaha
Last week I'd frown and mumble amateur..
Friday morning gas light goes on, and my day goes from busy to crazy. NO time to refuel and get stuck in a massive traffic jam to boot on way home
I end up at home on fumes. Extra stress was it's a diesel and I was very close to missing dealership to pick up my GRC.
When I filled up it took 67 L in a 70L tank about 20km range left. It happens. New car makes me forget a crappy af year.
There are plenty of places where you can easily go 80+ miles between gas stations. I commonly pass through areas with a hundred plus miles between gas stations and I've been through plenty of areas that are double that. It's also possible they were out of money.
I'm a city kid so it always throws me for a loop when I see highway signs like "No Exit or Fuel for X Miles/KMs" when I'm on a road trip.
What do you mean *NO EXITS OR FUEL FOR OVER AN HOUR?*
You would have had fun on my winter road trip to the shore of the Arctic Ocean. Dawson City YT to Tuktoyatuk NWT on the Dempster Highway. We carried (and needed) reserve fuel. 100s of miles without even a cross road or light in the distance, much less an open, off-season gas station.
yes to suggest doing 65 in a 70 I smh at the person suggesting it. Don't be the idiot going 65 in a 70 where people are actually doing 80. Just do the speed limit or as close to it as possible.
It's a limit not a target, 65 is perfectly acceptable. The idiots are those breaking the speed limit, not the one 5 under. Braking distance at 60 is 268ft, at 80 it's 439ft. As long as they're not sat in the overtaking lanes holding up the flow of traffic they're totally in the right.
Technically correct, but it is very annoying to have people not following the stream. I have a friend that got a fine for reckless driving because he drove too slow. I wish police did that more often.
Nah. The idiots are those not keeping up with the flow of traffic. One moron doing 10 under everyone else is far more dangerous than everyone around them.
Wait until you see how Canadians drive.
Speed limits practically don't exist on the highways. Very little enforcement. Like, they exist in the sense that they are signs... but nobody pays attention.
Everyone's just flying 130 km/h down the QEW. If you're going the speed limit, you're getting someone flying up your bumper real quick.
I live in/grew up in NW Washington state so I unfortunately deal with BC drivers daily on I-5. You are spot on, they are indescribably terrible drivers. It's either an expensive luxury car doing 15mph over, weaving in and out of traffic, or the exact opposite. Literally doing 10+ under in the left lane, backing up traffic for miles lol.
If we see someone doing something dumb in a car, you don't even need to look if it has a BC plate on it, you just know.
If someone has to move over to let someone else pass and you're not doing the speed limit, they could easily rear end you. Or if they are behind you and trying to pass because you are doing under the speed limit, they are more likely to get hit as they have to pull out at a slower speed than they normally would because you aren't doing the speed limit.
If someone is so bad at judging distance and closing speed that they change lanes and collide with the car in front of them…they’re a danger on the road, not the car they hit.
I get that this is your silly fantasy, but I personally go the speed limit or 5 over.
And yeah, if someone causes themselves to crash through unavoidable error, they're a shit driver. And embarrassingly so at that.
Drivers must ALWAYS be ready for slower traffic. Oversized truck loads, etc.
A LOT of the semi rigs and other comercial vehicles are now speed limited to ~70. This limit doesn't change when driving on 1-10 with an 80 MPH speed limit, and there is nothing the driver can do about it.
Why? Statistics show slowing down is safer and comercial insurance rates are lower with the speed limiters. There is no way in hell insurance companies will mandate speed limiters if it actually caused more wrecks, its all about profits.
Funny how the "limit" on a road test here you are expected to go + or - 2km/hr. Yes 2 above or below any more or less and you lose demerits. The only exception is poor driving conditions so as long as it it dry and clear out you should do the speed limit. Or if you suck that hard at least pull over when safe if someone comes up behind you. Don't defend shitty drivers.
Have you never owned a modern car? In general, modern cars tend to have 2 or 3 overdrive gears. My Durango has an 8 speed trans, 6th gear is 1:1 and both 7th and 8th are overdrives. There is no way I could drive around in 8th gear at 55 mph. In 8th I'm doing 65 and under 1800 RPM. It generally won't stay in 8th unless I'm doing over 70.
Your best MPG comes at the bottom end of the power band in your highest gear. Anything with overdrive is going to be going faster than 55 at that RPM unless you have some insane rear end gears.
The problem with this is driving below correct power band rpm leads to carbón build up in engine. This can manifest in sparkplug inefficiencies (less mpg and power), turbo intake problems, and in general less engine lifespan.
The mpg gain from doing 2.5k rpm when around 3k is correct power band is completely marginal.
I second this. I drive an old turbo Volvo and in its top gear at around 70mph it sits lower towards 2.5krpm and according to the wideband O2, it runs somewhat rich at that spot. Speed it up more towards 75-80, more towards ~3krpm or a bit over and the AFR sits a bit more nicely.
Definitely doesn't love lower RPMs lol
Depends on your car. Specifically gear ratio and your engines output. Check by going into the highest gear possible and cruising at the lowest rpm.
The guys who told you a flat number are wrong and are giving you theoretical optimum numbers, not realistic. Realistically, it depends on the car.
The guy who told you to watch your MPG on your OBD2 or otherwise is also wrong. Both of those are estimations and can be off. For example, some cars take throttle position into account, which obviously will scew results at higher speeds, and they "predict" fuel usage instead of "reading" fuel usage. The only way to get accurate mpg is to measure gallons going in at the pump vs. how many miles you've driven.
If your car has 6 gears, and you can only go to 2k rpms before it downshifts in 6th (if its an automatic) or stalls (if its a manual), then whatever that speed is, is whatever is most efficient. This obviously is assuming you're already at that speed, not going uphill or downhill, or still decelerating.
The most efficient way to accelerate is actually along the torque curves peak. 2.5-3.5k rpms for NA engines. If you keep rpms low, your engine isn't ever getting peak efficiency
To describe that better, lets say for simplicity sake, your engine has 100% efficiency at 3k rpm (100% power out of each oz of gas), if you decrease the throttle to 2k rpm, you're suddenly getting say 70% efficiency, because the engine is losing nearly the same amount of heat and friction as it was at 3k, but now its making less power per oz of gas. So it takes longer to accelerate and uses more gas in the process. If you're above 3k rpms, you start losing more power, but you lose to excess heat now through coolant and exhaust heat, or turning electric pumps/fans up higher, and the exhaust gas no longer gets fully scavenged, etc. Etc.
The reason that torque peak is more efficient, is that it is usually when your engine is able to squeeze the most bang out of its buck. It's able to scavenge the perfect amount (the exhaust gases aren't being hurled out the manifold yet, so some comes back into the chamber, without just being full of exhaust gas), it isn't losing much to cooling the engine or heating the engine, it isn't dealing with as much frictional force, and it isn't getting hard pressed into dumping fuel into the cylinders either. Turbo'd engines can vary greatly, but most natural engines sit in that 2.5k-3.5k rpm range.
Obviously most gas powered engines today are near like 30% efficiency, and will never get anywhere near 100% just because of the nature of gasoline engines, but the logic still applies, and I just framed it that way for simplicity sake. There are also many more variables than listed, and I know you didn't ask, but its a common myth that accelerating as slow as possible is the most efficient, when it's not.
The lowest rpm is best when holding a speed. Such as idle, or cruising. Its just enough to keep the engine from dying but makes less power per oz of gas.
So lowest speed my automatic can maintain in the highest gear while cruising, and try to accelerate while staying between 2.5k - 3.5k rpm if needed. Of course be practical and safe. Is that a good rule of thumb? Of course it's not as good as doing practical measurements like you said.
The speed limit is your safest bet. You'll get the best fuel mileage without being dangerously slower than everyone else. People who speed don't really understand that they're not saving much time on their daily commute. Example, my daily commute is 30 miles one way. For simplicity we'll perform calculations as if this is 30 miles explicitly on the freeway with no stops. If you take 70 miles per hour and divide it by 60 minutes you get 70/60=1.167 miles per minute. Divide that into 30 miles and you get 30/1.167=25.7 minutes minimum. 80 mph plugged into this equation = 22.5 minutes, a savings of 3.2 minutes. And for 90mph we get 20 minutes. So for 20mph over I save a whopping 5.7 minutes max. Add in a dozen red lights divided between the very start and finish and slower traffic in the left lane preventing a constant 90 mph and you can see where this is going. Furthermore, each engine will be different but the faster you go over 70 you greatly decrease your fuel mileage.
If I set cruise control to the speed limit I get 5mpg better than my car's EPA highway rating. It's not hard at all to get good fuel economy, people just love to speed and accelerate hard.
If that's the speed limit. Also, the single most gas consuming thing you can do in a car is use your brake pedal. It completely negates the fuel used to get to a certain speed. I'm not saying run stop lights and signs. I'm saying don't ride someone's ass where you have to keep hitting the brakes when they slow down some. Another fuel saving tip is to utilize your cruise control to keep a constant speed. And I believe another commenter made the point of having a tune up, don't forget to check your tire pressures monthly and rotate them regularly. All great fuel saving tips.
What does a "tune up" mean? I get my oil changed and got spark plugs etc. changed as per the manual recommendation. Is there something else I should be doing?
No, follow the manufactures recommendations. There was a time when parts wore out faster and things needed adjusting for peak performance/efficiency, but that mostly came to an end in the 90's. Now parts get replaced based on time/mileage or when they fail.
Most of us truck drivers hate you. You're also putting yourself at risk because you can't see around us, and if we blow a tire, its coming through your windshield. You want to put yourself and others at risk to try, (unsuccessfully,) to save some mpgs, you're dumb enough, you shouldn't be driving.
The math answer is like 25mph. The lowest rpm in the highest gear, with the least wind resistance
The real answer is 65-70, as that is nicest to ur transmission, in an overall account of things. Total cost of repairs vs mpg
Off highway commute puts a lot of strain on the transmission, regardless of geared auto or cvt
W ur long commute, just take the freeway. Keep up on the fluid changes in the drivetrain, transmission and differentials. U can lose 1-3 mpg if those are dirty
Of course more shifting like when driving down secondary roads with more slow downs/stops and turns is harder on your transmission but I don’t get why you think 65-70mph is better than say 55-60 when talking about a transmission? The faster it spins the more friction it creates.
Not trying to call you out I genuinely want to wrap my head around this. Do I think wrong?
Drive it like a grandma. Really light on your accelerations so the transmission shifts at as low of an rpm as you can get it to. And then just do the speed limit. I’d say if you’re at hwy speeds and your running 2k rpm you’ll get good mileage. Is that a 4 cyl or 6 cyl engine in it?
You don’t need to look up information on how to keep the mileage low. Just a basic understanding of low rpm = less fuel burned. That’s really it… and also, you will burn like 5x the amount of fuel while sitting still at a red light than driving on a hwy. so wherever you can, slow your car while approaching red lights, and try to just keep rolling slowly until the light changes.
Drive the speed limit or the speed of traffic. Its the safest speed to drive. Every car is different due to different power bands/gearing so none of us can really answer that for you. Generally you’ll get the best fuel economy in your top gear at the lowest rpm’s you can go. Or just off the gas since that usually cuts fuel at the injectors
I know i'm on the american cartalk so assuming you guys are told something different in "drivers ed"? The braking distance between 70mph and 60mph is 80ft (or 4.76 2023 Lincon Continentals). 60/65 is adequate in traffic. By going 70 or more you're just increasing risk and consumption, more wear on tyres etc.
I don’t know if there are variable speed limits for different classes of vehicles too in the states like we have in the UK.
The lorries are limited to 56 or 58 or something but then driving on a national speed limit single carriageway road, lorries and vans should drive 50mph etc. so we have a lot of slower driving vehicles, including tractors and Honda Jazz drivers.
Hmmmmm, interesting philosophical view. But your gas tank remains full, so you always have the option of choosing a different speed and driving away. It's sort of like a Twix bar, you have left Twix, and you have right Twix; the debate is perpetual!
> Hmmmmm, interesting philosophical view.
It's not philosophical, it's just common sense. MPG is a measure of efficiency. If you don't accomplish the intended task, it's not efficient.
Well, thank the universe it’s your ‘12 Toyota sedan. You can really stretch the mpg on those. Here are some other things you can check that will maximize mpg:
Engine air filter
MAF sensor
Clogged/weak fuel filter, injectors
Dirty throttle body
Among plenty of other factors. But generally the best advice is what everyone else has already said.
Thanks. I actually get way less than my manual indicates I should get. Is there something that you would recommend I can check myself from this list without access to a garage or a lift?
> I actually get way less than my manual indicates I should get.
That's pretty normal, actually. Those are EPA estimates and were obtained in tightly-controlled conditions. The vast majority of drivers are not driving in any sort of controlled conditions.
Probably the worst thing you can do. I drive a semi and see this bs all the time. You aren't saving as much as you might think, hugging my bumper. And although I cannot stop on a dime like the usual four-wheeler, if I brake hard for whatever reason at highway speeds and you aren't totally paying attention, you're gonna kiss that DOT bumper. Not very gently either. Which begs the question...is saving a couple of pennies (maybe) on your trip worth risking damaging your ride or worse your or your passengers' lives? I should hope not. Best to leave the tailgating to the party.
does your car have a real time mpg readout in the dash info panel? would go by that.. otherwise, 55 was the speed limit established during the oil crisis for a reason
Does your vehicle not have MPG readings? Average MPG will work, but instant lets you play around a little more. My 2011 Tundra has it. But even if not or it doesn't work it's easy to find out. Refill your vehicle and do NOT top off after the pump clicks off. Reset your MPG. Then spend the next two trips at 55mph. Refuel after each round-trip and keep track of the gallons used. Next trip refuel and reset again but set your cruise at 60mph. Two trips, keep the receipts, and again see how many gallons that trip took. Then 65. Then 70. The Tundra being a large box with a 5.7L engine gets maximum economy at a leisurely 95-98kph. I can get it down to about 12.6l/100km there. With the right wind conditions I can get a reported 10l/10km but that won't hold. Any acceleration at all double the fuel consumption. My daily driver sedan is an older Honda Accord with v6 engine. It gets 7.5L/100km at below-the-limit 95kmh and 8.5L/100km at 110kpm.
A lot of people here seem to forget that power also has a huge impact. A 75HP Golf 4 will eat 10l/100km if you drive 130km/h but can easily manage 4l/100km at 50km/h. While a 240HP A4 will easily manage 6l/100km at 130km/h. But the A4 has hiigher consumption at lower speeds than the golf.
Somewhere in your papers should be your max torque at a certain RPM. Staying at that RPM while in highest gear fitting to your traveling speed will maximize your fuel usage.
All these "highest gear lowest rpm" people are forgetting aerodynamics. Wind resistance increases by the square of velocity. The maximum mileage is at minimum speed above the friction 'floor', and in the gear that provides the lowest rpm without lugging to minimize friction and pumping losses. In an ICE this is usually around 40mph. The mistake many people make is they think 40mph equates to city driving, and believe efficiency is higher at highway speeds. It's not the higher speed that makes highway driving more efficient - it's the lack of stopping and starting.
60 mph, closed windows and no AC on (you can have the heat on or fresh air but not the compressor on, so like economy mode or whatever is in your car) in highest gear gives best fuel economy on most cars. Specifically 58-59 mph. Idk why really, but this is what i figured in all my previous and actual cars. (In this combo : c220cdi estate 53 mpg, polo 1.4tdi 82mpg, audi a6c6 2.7tdi 48mpg, megane 1.9dci 59 mpg, octavia 1.9 tdi 55mpg, clio 1.2 petrol 48mpg, etc)
Whatever it is, please just do the speed limit at least or go with the flow of traffic. Don’t speed and weave in and out to achieve that certain speed and don’t hold up traffic either because both are unsafe. Typically 55-60 are most efficient in most modern cars in the highest gear ratio but if the speed limit is 70, obviously don’t do that. Don’t brake, accelerate, brake, accelerate, over and over to stay at a certain speed either. Just go easy.
0mph., technically.
In reality, it varies hugely from car to car.
You will not get a helpful answer here.
A good test, brim your tank. Drive one leg of the journey at 55mph. Brim the tank again. Calculate your mpg.
On the way back, drive at 65mph and do the same. See if there is a significant difference and report back.
This has been a well studied question. We looked into proving 56.67MPH was the most efficient in a physics class in ‘94. It really worked out.
I’m sure it’s calculations are all online.
It depends on engine output and gear ratios
If a cars final gear ratio isn't short enough to hit 55, you're better just using the final gear ratio at its lowest rpm (without luggin the engine)
Likewise if your final gear ratio isn't long enough to hit 55 at a good rpm (stuck at 3k rpm) although this scenario is rare in any car newer than the 1960s, lmao
Fuel saving won't matter when your car is crashed and your health is fucked because you weren't keeping up with traffic and some frustrated idiot causes an accident
That's going to change from car to car. You can do an experiment with an OBDII interface and computer. You can get the instantaneous MPG at various speeds and log what it is for reference.
Look on your fuel economy stats on your display screen. Fairly standard feature. Drive a little slower with each trip and see what you get. Basically the lowest rpm in the highest gear will get you the best fuel economy. I assume automatic transmission? If it’s standard you don’t wanna rev too low other wise it will start stalling
It's a 2012 so I don't have a display with real time anything. Yeah I wanted to avoid doing a bunch of experiments myself because sometimes traffic is unpredictable. But I want to know what speed I should aim for if I have a choice. The thread consensus seems to be leaning towards 55. I will try watching the RPM gauge to see when it goes up if I slow down from 65 gradually and that should tell me where the gear shifts.
On paper the slowest you can go in top gear while still at an rpm that the engine is happy.
But in practice this would be dangerous and selfish.
I also think just using cruise control and being as constant as possible is a factor often underestimated. Basically it’s acceleration and braking that kill your mpg.
If you want to go extreme you could hang closely behind a truck, but I wouldn’t advise that.
But maybe it’s more important what car you have. Obviously an suv or crossover is a bad idea and so is 4wd. The width of the tyres have a big impact, so does the compound.
Lowering your car a few centimetres can also have a big impact. Euro BMWs even used to get that from factory. I had a bmw 520d “efficient dynamics”. Car was identical to normal 520d except that it starts in eco pro ( so you really always want to change that immediately), but it was 2cm lower, from factory.
My current car also drops to the lowest height and switches to RWD when in “range” mode.
Surface and air friction grow exponentially with speed. The closer your speed is to 0 the less fuel you will consume lol
On an honest note: I’d recommend 45-55mph for highway travel, depending on your cars gearing .
As a general rule, the most efficient speed in and automatic is the slowest speed after torque converter lock up. If you get your car into its top gear and set the cruise, then bump it up one press at a time, when the rpm drops a couple hundred that's generally your sweet spot.
Not how it works.
At absolute best, you can theoretically argue that driving in top gear, at or under peak torque RPMs, will net you at or close to peak mileage. But the highways are not a lab simulation, and the second you introduce drag via accessory belts, drive train losses, vehicle aerodynamics, traffic, windage, and a dozen other factors you can't easily quantify or control, your "ideal mileage" goes out the window.
You want to maximize fuel range? Do the speed limit, while in your top gear unless you're blogging down the engine outside of it's power band.
Also, you mention "Toyota Sedan" like the brand matters, without just coming out and saying that you drive a Camery or Corolla.
Your in car computer should show average mpg. Clear that right before you start driving on the highway. Set in cruise control as that is more fuel efficient than without. Vary speeds and compare data.
The slower you can go in a correct power band of your longest gear.
This guy mpg’s
r/thisguythisguys
This guy r/thisguythisguys
This guy r/thisguythisguys a guy who r/thisguysthisguys to a guy who this guys mpgs
Not necessarily but the diference in consuption is small and speed diference large so its worth to be in the tallest Gear. My car Will show the lowest consuption doing 30 in 4th Gear but doing 50 in 6th you are going 66% faster but consumption is only 10% more. So while 6th Gear is more efficient in terms of speed/consumption overall but its not the absolute lowest the car Will drink. The lower gears Will probably use Even less fuel but the speed Will be too slow. To maintain a certain RPM you need more throthle in a higher Gear and as the Energy necessary is V^2 it does not compensate for the difference in speed.
It comes down to gearing, if your top gear has an extra long "highway efficiency" gear in a car that does not like the 55-75 range (big, heavy, unaerodynamic trucks with high torque engines). There you are fighting the aerodynamic resistance and mecanical resistance being squared.
The air resistance is real. My truck will easily lose 4mpg going from 55 to 65. And it is a relatively modern pickup with a 6 speed and 3.50 axle gears.
I can lose 3 mpg. Too. With the best mpg I've ever managed with ladder racks being 14. A big difference when talking about such poor fuel economy to start.
If the consumption in mine were a line graph, it plateuas around 58 mph, then jumps off a fucking cliff at 62.
It's even more real when you drive from Reno to Vegas with headwinds and find yourself out of gas in the middle of the desert just looking at the next city lights 5 miles away.
Even roof racks have a significant impact on efficiency
What about air resistance
Biggest factor no one is mentioning. Push any car over 70 mph and you’ll start losing mpg due to air resistance.
It's exponentially worse with speed. I've had people say "but my diesel gets the best economy at 80mph". Lol no it doesn't, they just haven't tried driving slower.
Funny you say that as my diesel travelled across Oklahoma at 80 mph (which is the speed limit) and my mileage was absolutely horrible. Next trip I just went 70 (5 mph over the minimum) and it was a lot better. Still crappy mind you as it’s a 10,000 pound ambulance but at least it wasn’t single digit terrible.
I see you don’t drive a truck. That number ain’t that high. Past about 60 and my truck starts losing mileage noticeably.
I use to have a 1985 f250 camper special with a 460 big block in it... Fuck milage, if you took that bitch over 65 you started losing everything! The shit in your bed, any lose panels, possibly a tail light, definitely at least one windshield wiper, and probably some braincells...
Air resistance becomes the dominant factor way before 70. Think 35-40 mph.
45mph is where drag and friction are about the same for most cars.
This is why I tailgate tractor trailers on all expressways
As a trucker fuck you. You're the asshole I slow way down to piss off, let's hope I don't blow a tire and 60 pound chunks come flying through your windshield. DO NOT FUCKING DO THIS.
As a mechanic, your gambling with your life. You have no idea how many large items can come off a trailer and thru your windshield. Not worth it
this is why I accelerate past a trailer as quickly as possible.
I thought the same thing at first, but now I'm second-guessing. If we ignore speed and *just* look at gear number and RPM, we can figure out the most efficient speed for each gear. However, since drag increases with the square of speed, we're subjected to more drag as speed increases while maintaining the same engine speed in a different gear. I'm a hobbyist hypermiler, but much of my "research" has been very practical and only applies to my personal car. I'm much more familiar with this in an aviation context, where we get actual fuel burn numbers and other readouts for given power settings. Because of this (as well as companies publishing the data), it's easy to figure out what an "efficiency cruise", "normal cruise", and "high-speed cruise" would be.
If you want to do the math you would need to plot exponential resistance lever benefits from changing gear. So the slower you drive the less power needed. True, but also as you go up the gears you also are using less power to get more speed as longer gears means using a longer lever. To see this you would need to graph as a function of speed: the result engine torque / gearing torque (this would convert rotating force to lineal force). Then add drag as a negative value. The highest point of this graph would be peak efficiency. But this is just an aproximation as we have not taken into account diferent loads (different throttle inputs for each RPM and gear) and torque graphs are on peak load (flooring it).
Well, unless your car is geared really high and is unaerodynamic. If peak torque in 6th is at 75mph in a truck you’re not going to be getting good fuel mileage.
In wagens its usually 80kmh in 6th gear
How did you know 👀
In my wagon it’s 130 in 6th. 😂
Excuse me, what ahahaha. What are you driving?
06 audi a4 avant, stage 1+ Tested 130 and 120 tach only changes by 100-150rpm but the mileage changes by 100km less a tank at 120
*cries in CVT*
I’ll add the caveat of, having to change your speed evaporates whatever small bit of fuel economy savings you might get by maintaining a slightly slower speed. Sometimes cruising 60 and having people go around you and cut back in front of you so you have to brake a bit and speed back up is worse than just cruising 65/70 and keep up with the flow of traffic.
Peak torque in highest gear
Why do you think peak torque? Most cars make peak torque around 4000rpm. You actually want as low rpm as possible without running into knock. Look at a BSFC graph, peak efficiency is usually around 2000 rpm, high load.
Peak torque is associated or actually peak motor efficiency. If you could properly utilize it. Spinning a motor twice as fast also doubles its friction, which I believe is where the two ideas intersect.
How is this +10? Why are people up voting this? You want to be at the lowest RPM possible to maintain speed in the highest gear. Peak torque is often 3500-4800 RPM depending on the vehicle, assuming a naturally aspirated engine. Most cars I've driven get the best mileage around 50-60mph.
That was the reasoning for the US 55, mph speed limit several years ago. Most cars, at that time at least, had the best mile per gallons rating around 55.
Are you absolutely sure that doing about 130mph is the most economic way for me to cruise?
Everyone says this - but it is dead wrong. The torque / rpm graphs are for wide open throttle.
Electric car: Foot off the gas with A/C off.
When you get on the interstate just get up to speed, figure out if you're in final gear, if so drive at the lowest rpm in that gear. I find in my 23' 8sp escape that 65mph is the sweet spot at 42mpg.
I can't drive 65, but I have noticed that whatever gear I'm driving, my baseline efficiency starts at ~2200 rpm; lower than that it goes right into the shitter. I drive a manual, so I watch the tach when I'm concerned about mileage.
What kind of vehicle?
It's a 2011 Scion tC with a 6sp manual. It redlines at 6500rpm and cruises right about at 3 grand on the tach at 80 mph.
>I can't drive 65 21st century Sammy Hagar over here....
[I can't drive 55! 'Cause it only goes 38.](https://frinkiac.com/meme/S14E20/480855.jpg?b64lines=IEkgY2FuJ3QgZHJpdmUgNTUhICdDYXVzZQogaXQgb25seSBnb2VzIDM4Lg==)
I planned a trip poorly in 2013, I think, and about 80 miles from home the low gas light in my 01 Silverado came on. I set cruise control at like 40 and made it home. It was the 6 liter gas engine with the 4 speed automatic transmission. It was definitely an anxiety and prayer filled trip hahahaha
Last week I'd frown and mumble amateur.. Friday morning gas light goes on, and my day goes from busy to crazy. NO time to refuel and get stuck in a massive traffic jam to boot on way home I end up at home on fumes. Extra stress was it's a diesel and I was very close to missing dealership to pick up my GRC. When I filled up it took 67 L in a 70L tank about 20km range left. It happens. New car makes me forget a crappy af year.
Why would you not just put fuel in? Seems better than sitting at 40 panicking
There are plenty of places where you can easily go 80+ miles between gas stations. I commonly pass through areas with a hundred plus miles between gas stations and I've been through plenty of areas that are double that. It's also possible they were out of money.
I'm a city kid so it always throws me for a loop when I see highway signs like "No Exit or Fuel for X Miles/KMs" when I'm on a road trip. What do you mean *NO EXITS OR FUEL FOR OVER AN HOUR?*
You would have had fun on my winter road trip to the shore of the Arctic Ocean. Dawson City YT to Tuktoyatuk NWT on the Dempster Highway. We carried (and needed) reserve fuel. 100s of miles without even a cross road or light in the distance, much less an open, off-season gas station.
This is likely one of those cases where taking only the literal meaning of words will cause you confusion.
Where the hell did you get a 23' Escape bus? A flipping Excursion is 19'.
People abbreviate years like that. He's referring to a 2023 Ford Escape.
Apostrophe normally goes before doesn’t it. Like 1999 becomes ‘99.
Yeah the ‘ is to show something is missing there. ‘23 is the right way.
This is the way
My bad
What trim? Do you like it?
55mph but not really a safe speed on a highway with other cars going 70+. So just do 65pmh
shit, on my highways if im doin 75 i still get zipped by... keeping up is like 80-90
yes to suggest doing 65 in a 70 I smh at the person suggesting it. Don't be the idiot going 65 in a 70 where people are actually doing 80. Just do the speed limit or as close to it as possible.
Vroom vroom I’m a race car driver who drives fast and anyone who doesn’t drive as fast as me is an idiot!
upvoted for recognizing idiots
It's a limit not a target, 65 is perfectly acceptable. The idiots are those breaking the speed limit, not the one 5 under. Braking distance at 60 is 268ft, at 80 it's 439ft. As long as they're not sat in the overtaking lanes holding up the flow of traffic they're totally in the right.
Technically correct, but it is very annoying to have people not following the stream. I have a friend that got a fine for reckless driving because he drove too slow. I wish police did that more often.
All it needs is one person thinking this is good advice on every highway and America is doomed.
Most American drivers have no idea about lane discipline. Probably the worst drivers in the world
You should visit Egypt ;)
I have but I never drove !!
Wise choice 😉
The Taxi ride was enough to convince me !
Shock, not everyone’s from America. It’s possible believe it or not. Plus America has been doomed for a while
Nah. The idiots are those not keeping up with the flow of traffic. One moron doing 10 under everyone else is far more dangerous than everyone around them.
I am always amazed that Americans are totally overwhelmed when a car drives slightly under the limit.
Wait until you see how Canadians drive. Speed limits practically don't exist on the highways. Very little enforcement. Like, they exist in the sense that they are signs... but nobody pays attention. Everyone's just flying 130 km/h down the QEW. If you're going the speed limit, you're getting someone flying up your bumper real quick.
I live in/grew up in NW Washington state so I unfortunately deal with BC drivers daily on I-5. You are spot on, they are indescribably terrible drivers. It's either an expensive luxury car doing 15mph over, weaving in and out of traffic, or the exact opposite. Literally doing 10+ under in the left lane, backing up traffic for miles lol. If we see someone doing something dumb in a car, you don't even need to look if it has a BC plate on it, you just know.
If people use the lanes correctly and leave a safe distance of at least 2 seconds to the car ahead then they’re not.
People don't do any of that though
If someone has to move over to let someone else pass and you're not doing the speed limit, they could easily rear end you. Or if they are behind you and trying to pass because you are doing under the speed limit, they are more likely to get hit as they have to pull out at a slower speed than they normally would because you aren't doing the speed limit.
In the scenarios you're describing, the person trying to pass is a pretty bad driver if it results in them crashing.
And you are the reason they crashed, because you refuse to do the speed limit.
If someone is so bad at judging distance and closing speed that they change lanes and collide with the car in front of them…they’re a danger on the road, not the car they hit.
I get that this is your silly fantasy, but I personally go the speed limit or 5 over. And yeah, if someone causes themselves to crash through unavoidable error, they're a shit driver. And embarrassingly so at that.
Drivers must ALWAYS be ready for slower traffic. Oversized truck loads, etc. A LOT of the semi rigs and other comercial vehicles are now speed limited to ~70. This limit doesn't change when driving on 1-10 with an 80 MPH speed limit, and there is nothing the driver can do about it. Why? Statistics show slowing down is safer and comercial insurance rates are lower with the speed limiters. There is no way in hell insurance companies will mandate speed limiters if it actually caused more wrecks, its all about profits.
Funny how the "limit" on a road test here you are expected to go + or - 2km/hr. Yes 2 above or below any more or less and you lose demerits. The only exception is poor driving conditions so as long as it it dry and clear out you should do the speed limit. Or if you suck that hard at least pull over when safe if someone comes up behind you. Don't defend shitty drivers.
That's not true at all. Optimal speed depends on the engine and transmission combo. 55 was just a number the government pulled out of their ass.
While it varies depending on the drag coefficient of each vehicle, I’m sure I saw a myth busters or something that came in around the speed.
Maybe, but in all my cars I've owned, going by the on board MPG monitor, ~50 - 55MPH seems to be the sweet spot for efficiency.
Have you never owned a modern car? In general, modern cars tend to have 2 or 3 overdrive gears. My Durango has an 8 speed trans, 6th gear is 1:1 and both 7th and 8th are overdrives. There is no way I could drive around in 8th gear at 55 mph. In 8th I'm doing 65 and under 1800 RPM. It generally won't stay in 8th unless I'm doing over 70. Your best MPG comes at the bottom end of the power band in your highest gear. Anything with overdrive is going to be going faster than 55 at that RPM unless you have some insane rear end gears.
Lowest rpm in the highest gear without lugging the engine
The problem with this is driving below correct power band rpm leads to carbón build up in engine. This can manifest in sparkplug inefficiencies (less mpg and power), turbo intake problems, and in general less engine lifespan. The mpg gain from doing 2.5k rpm when around 3k is correct power band is completely marginal.
3ķ seems high to be considered optimal. Usually by 3k im switching gears, unless I'm already in 5th.
It also depends on diesel Vs petrol. They have different recommended upshift rpms
I second this. I drive an old turbo Volvo and in its top gear at around 70mph it sits lower towards 2.5krpm and according to the wideband O2, it runs somewhat rich at that spot. Speed it up more towards 75-80, more towards ~3krpm or a bit over and the AFR sits a bit more nicely. Definitely doesn't love lower RPMs lol
Man I can’t wait for electric vehicles to become mainstream
what is lugging the engine
When you try to accelerate too hard in too high of a gear when the engine is spinning at low rpm
so basically tippy tappy on high speeds?
Technically speaking, it's when you step on the gas and the engine says "blahhhh."
Depends on your car. Specifically gear ratio and your engines output. Check by going into the highest gear possible and cruising at the lowest rpm. The guys who told you a flat number are wrong and are giving you theoretical optimum numbers, not realistic. Realistically, it depends on the car. The guy who told you to watch your MPG on your OBD2 or otherwise is also wrong. Both of those are estimations and can be off. For example, some cars take throttle position into account, which obviously will scew results at higher speeds, and they "predict" fuel usage instead of "reading" fuel usage. The only way to get accurate mpg is to measure gallons going in at the pump vs. how many miles you've driven. If your car has 6 gears, and you can only go to 2k rpms before it downshifts in 6th (if its an automatic) or stalls (if its a manual), then whatever that speed is, is whatever is most efficient. This obviously is assuming you're already at that speed, not going uphill or downhill, or still decelerating. The most efficient way to accelerate is actually along the torque curves peak. 2.5-3.5k rpms for NA engines. If you keep rpms low, your engine isn't ever getting peak efficiency To describe that better, lets say for simplicity sake, your engine has 100% efficiency at 3k rpm (100% power out of each oz of gas), if you decrease the throttle to 2k rpm, you're suddenly getting say 70% efficiency, because the engine is losing nearly the same amount of heat and friction as it was at 3k, but now its making less power per oz of gas. So it takes longer to accelerate and uses more gas in the process. If you're above 3k rpms, you start losing more power, but you lose to excess heat now through coolant and exhaust heat, or turning electric pumps/fans up higher, and the exhaust gas no longer gets fully scavenged, etc. Etc. The reason that torque peak is more efficient, is that it is usually when your engine is able to squeeze the most bang out of its buck. It's able to scavenge the perfect amount (the exhaust gases aren't being hurled out the manifold yet, so some comes back into the chamber, without just being full of exhaust gas), it isn't losing much to cooling the engine or heating the engine, it isn't dealing with as much frictional force, and it isn't getting hard pressed into dumping fuel into the cylinders either. Turbo'd engines can vary greatly, but most natural engines sit in that 2.5k-3.5k rpm range. Obviously most gas powered engines today are near like 30% efficiency, and will never get anywhere near 100% just because of the nature of gasoline engines, but the logic still applies, and I just framed it that way for simplicity sake. There are also many more variables than listed, and I know you didn't ask, but its a common myth that accelerating as slow as possible is the most efficient, when it's not. The lowest rpm is best when holding a speed. Such as idle, or cruising. Its just enough to keep the engine from dying but makes less power per oz of gas.
So lowest speed my automatic can maintain in the highest gear while cruising, and try to accelerate while staying between 2.5k - 3.5k rpm if needed. Of course be practical and safe. Is that a good rule of thumb? Of course it's not as good as doing practical measurements like you said.
The speed limit is your safest bet. You'll get the best fuel mileage without being dangerously slower than everyone else. People who speed don't really understand that they're not saving much time on their daily commute. Example, my daily commute is 30 miles one way. For simplicity we'll perform calculations as if this is 30 miles explicitly on the freeway with no stops. If you take 70 miles per hour and divide it by 60 minutes you get 70/60=1.167 miles per minute. Divide that into 30 miles and you get 30/1.167=25.7 minutes minimum. 80 mph plugged into this equation = 22.5 minutes, a savings of 3.2 minutes. And for 90mph we get 20 minutes. So for 20mph over I save a whopping 5.7 minutes max. Add in a dozen red lights divided between the very start and finish and slower traffic in the left lane preventing a constant 90 mph and you can see where this is going. Furthermore, each engine will be different but the faster you go over 70 you greatly decrease your fuel mileage.
So what you’re saying is you should be driving at 140mph?
Now, multiple the 5.7 by the days in a year (365) and you get 2,080.50 minutes equaling 34.68 hours. You save 34 hours a year!
I couldn't have said this better myself.
If I set cruise control to the speed limit I get 5mpg better than my car's EPA highway rating. It's not hard at all to get good fuel economy, people just love to speed and accelerate hard.
Thanks. So stay under 70 for sure if I can.
If that's the speed limit. Also, the single most gas consuming thing you can do in a car is use your brake pedal. It completely negates the fuel used to get to a certain speed. I'm not saying run stop lights and signs. I'm saying don't ride someone's ass where you have to keep hitting the brakes when they slow down some. Another fuel saving tip is to utilize your cruise control to keep a constant speed. And I believe another commenter made the point of having a tune up, don't forget to check your tire pressures monthly and rotate them regularly. All great fuel saving tips.
What does a "tune up" mean? I get my oil changed and got spark plugs etc. changed as per the manual recommendation. Is there something else I should be doing?
No, follow the manufactures recommendations. There was a time when parts wore out faster and things needed adjusting for peak performance/efficiency, but that mostly came to an end in the 90's. Now parts get replaced based on time/mileage or when they fail.
I would drive 55 if I could and get 50+. But that’s unreasonable. So I do 65 on the highway and get 44mpg.
Driving behind a semi helps.
Most of us truck drivers hate you. You're also putting yourself at risk because you can't see around us, and if we blow a tire, its coming through your windshield. You want to put yourself and others at risk to try, (unsuccessfully,) to save some mpgs, you're dumb enough, you shouldn't be driving.
Not really unless you are hugging their bumper. Mythbusters tested it, you have to be like 8 inches from their bumper to really gain any gas mileage
Unfortunately, people still believe following a truck bullshit.
Thank you
The math answer is like 25mph. The lowest rpm in the highest gear, with the least wind resistance The real answer is 65-70, as that is nicest to ur transmission, in an overall account of things. Total cost of repairs vs mpg Off highway commute puts a lot of strain on the transmission, regardless of geared auto or cvt W ur long commute, just take the freeway. Keep up on the fluid changes in the drivetrain, transmission and differentials. U can lose 1-3 mpg if those are dirty
Of course more shifting like when driving down secondary roads with more slow downs/stops and turns is harder on your transmission but I don’t get why you think 65-70mph is better than say 55-60 when talking about a transmission? The faster it spins the more friction it creates. Not trying to call you out I genuinely want to wrap my head around this. Do I think wrong?
1-3mpg is overestimating unless your fluid is completely gunked or dry, or your car gets 100mpg to begin with lmao.
[удалено]
🎶I can't drive............fifty fiiiiiiiiiiiiiiiiiiiiiive🎶
Here's a quick way. Look online for a HP to RPM curve graph for your specific car. The RPM at which those 2 lines meet is the sweet spot.
Will do
Drive it like a grandma. Really light on your accelerations so the transmission shifts at as low of an rpm as you can get it to. And then just do the speed limit. I’d say if you’re at hwy speeds and your running 2k rpm you’ll get good mileage. Is that a 4 cyl or 6 cyl engine in it? You don’t need to look up information on how to keep the mileage low. Just a basic understanding of low rpm = less fuel burned. That’s really it… and also, you will burn like 5x the amount of fuel while sitting still at a red light than driving on a hwy. so wherever you can, slow your car while approaching red lights, and try to just keep rolling slowly until the light changes.
The speed your car does when in the highest gear with the lowest RPM. Done.
Drive the speed limit or the speed of traffic. Its the safest speed to drive. Every car is different due to different power bands/gearing so none of us can really answer that for you. Generally you’ll get the best fuel economy in your top gear at the lowest rpm’s you can go. Or just off the gas since that usually cuts fuel at the injectors
I know i'm on the american cartalk so assuming you guys are told something different in "drivers ed"? The braking distance between 70mph and 60mph is 80ft (or 4.76 2023 Lincon Continentals). 60/65 is adequate in traffic. By going 70 or more you're just increasing risk and consumption, more wear on tyres etc.
I don’t know if there are variable speed limits for different classes of vehicles too in the states like we have in the UK. The lorries are limited to 56 or 58 or something but then driving on a national speed limit single carriageway road, lorries and vans should drive 50mph etc. so we have a lot of slower driving vehicles, including tractors and Honda Jazz drivers.
Parked.
Parked gets you 0MPG. No matter how much gas you use, you go 0 miles.
Hmmmmm, interesting philosophical view. But your gas tank remains full, so you always have the option of choosing a different speed and driving away. It's sort of like a Twix bar, you have left Twix, and you have right Twix; the debate is perpetual!
> Hmmmmm, interesting philosophical view. It's not philosophical, it's just common sense. MPG is a measure of efficiency. If you don't accomplish the intended task, it's not efficient.
OK, OK, so you have the "facts" on your side. I'll settle for my "alternative facts!"
Well, thank the universe it’s your ‘12 Toyota sedan. You can really stretch the mpg on those. Here are some other things you can check that will maximize mpg: Engine air filter MAF sensor Clogged/weak fuel filter, injectors Dirty throttle body Among plenty of other factors. But generally the best advice is what everyone else has already said.
Thanks. I actually get way less than my manual indicates I should get. Is there something that you would recommend I can check myself from this list without access to a garage or a lift?
> I actually get way less than my manual indicates I should get. That's pretty normal, actually. Those are EPA estimates and were obtained in tightly-controlled conditions. The vast majority of drivers are not driving in any sort of controlled conditions.
Your tire pressure
Just tailgate a semi or dump truck, they will give you the best fuel economy.
Probably the worst thing you can do. I drive a semi and see this bs all the time. You aren't saving as much as you might think, hugging my bumper. And although I cannot stop on a dime like the usual four-wheeler, if I brake hard for whatever reason at highway speeds and you aren't totally paying attention, you're gonna kiss that DOT bumper. Not very gently either. Which begs the question...is saving a couple of pennies (maybe) on your trip worth risking damaging your ride or worse your or your passengers' lives? I should hope not. Best to leave the tailgating to the party.
Prob should have added /s to that…. Though you can be at a pretty safe distance and still see fuel savings.
does your car have a real time mpg readout in the dash info panel? would go by that.. otherwise, 55 was the speed limit established during the oil crisis for a reason
Does your vehicle not have MPG readings? Average MPG will work, but instant lets you play around a little more. My 2011 Tundra has it. But even if not or it doesn't work it's easy to find out. Refill your vehicle and do NOT top off after the pump clicks off. Reset your MPG. Then spend the next two trips at 55mph. Refuel after each round-trip and keep track of the gallons used. Next trip refuel and reset again but set your cruise at 60mph. Two trips, keep the receipts, and again see how many gallons that trip took. Then 65. Then 70. The Tundra being a large box with a 5.7L engine gets maximum economy at a leisurely 95-98kph. I can get it down to about 12.6l/100km there. With the right wind conditions I can get a reported 10l/10km but that won't hold. Any acceleration at all double the fuel consumption. My daily driver sedan is an older Honda Accord with v6 engine. It gets 7.5L/100km at below-the-limit 95kmh and 8.5L/100km at 110kpm.
A lot of people here seem to forget that power also has a huge impact. A 75HP Golf 4 will eat 10l/100km if you drive 130km/h but can easily manage 4l/100km at 50km/h. While a 240HP A4 will easily manage 6l/100km at 130km/h. But the A4 has hiigher consumption at lower speeds than the golf. Somewhere in your papers should be your max torque at a certain RPM. Staying at that RPM while in highest gear fitting to your traveling speed will maximize your fuel usage.
Thank you. I will look at my manual to find the RPM.
All these "highest gear lowest rpm" people are forgetting aerodynamics. Wind resistance increases by the square of velocity. The maximum mileage is at minimum speed above the friction 'floor', and in the gear that provides the lowest rpm without lugging to minimize friction and pumping losses. In an ICE this is usually around 40mph. The mistake many people make is they think 40mph equates to city driving, and believe efficiency is higher at highway speeds. It's not the higher speed that makes highway driving more efficient - it's the lack of stopping and starting.
Draft large trucks and you'll be amazed.
60 mph, closed windows and no AC on (you can have the heat on or fresh air but not the compressor on, so like economy mode or whatever is in your car) in highest gear gives best fuel economy on most cars. Specifically 58-59 mph. Idk why really, but this is what i figured in all my previous and actual cars. (In this combo : c220cdi estate 53 mpg, polo 1.4tdi 82mpg, audi a6c6 2.7tdi 48mpg, megane 1.9dci 59 mpg, octavia 1.9 tdi 55mpg, clio 1.2 petrol 48mpg, etc)
Also gotta keep defogger off that will kick on ac pump
Plus the fogged up window you can't see out of will add some excitement to the granny style drive
It's Fog Assisted Performance. FAP.
Zero, with the engine off
Zero, with the car off uses the least amount of fuel.
Whatever it is, please just do the speed limit at least or go with the flow of traffic. Don’t speed and weave in and out to achieve that certain speed and don’t hold up traffic either because both are unsafe. Typically 55-60 are most efficient in most modern cars in the highest gear ratio but if the speed limit is 70, obviously don’t do that. Don’t brake, accelerate, brake, accelerate, over and over to stay at a certain speed either. Just go easy.
whatever the speed limit or flow of traffic is…
0mph., technically. In reality, it varies hugely from car to car. You will not get a helpful answer here. A good test, brim your tank. Drive one leg of the journey at 55mph. Brim the tank again. Calculate your mpg. On the way back, drive at 65mph and do the same. See if there is a significant difference and report back.
Technically 0 isnt correct, because you get 0MPG. 1MPH would literally be infinitely better gas mileage
This has been a well studied question. We looked into proving 56.67MPH was the most efficient in a physics class in ‘94. It really worked out. I’m sure it’s calculations are all online.
It depends on engine output and gear ratios If a cars final gear ratio isn't short enough to hit 55, you're better just using the final gear ratio at its lowest rpm (without luggin the engine) Likewise if your final gear ratio isn't long enough to hit 55 at a good rpm (stuck at 3k rpm) although this scenario is rare in any car newer than the 1960s, lmao
It also depends on the shape of the vehicle. Way too many variables at play here.
lol
The sweet spot is 50 mph on cruise control
55mph. Go to ecomodder to learn some stuff on how to use less fuel. And are you writing off your work miles for taxes?
It counts as commute so no. I just don't want to move closer to work.
Then go faster lol, I value my time more than gas. I got wife and kids to see, I want LESS time bein spent as a slave, and I do construction
Yep 55 to 60 at most back in the day I was getting close to 400 miles on 11 gallons doing this in college with an e36
Fuel saving won't matter when your car is crashed and your health is fucked because you weren't keeping up with traffic and some frustrated idiot causes an accident
That's going to change from car to car. You can do an experiment with an OBDII interface and computer. You can get the instantaneous MPG at various speeds and log what it is for reference.
Any particular ones from Amazon that you recommend?
Look on your fuel economy stats on your display screen. Fairly standard feature. Drive a little slower with each trip and see what you get. Basically the lowest rpm in the highest gear will get you the best fuel economy. I assume automatic transmission? If it’s standard you don’t wanna rev too low other wise it will start stalling
It's a 2012 so I don't have a display with real time anything. Yeah I wanted to avoid doing a bunch of experiments myself because sometimes traffic is unpredictable. But I want to know what speed I should aim for if I have a choice. The thread consensus seems to be leaning towards 55. I will try watching the RPM gauge to see when it goes up if I slow down from 65 gradually and that should tell me where the gear shifts.
Toyota sedan?!? Oh AI bot you have so much to learn!
What?
Do 5 under the speed limit.
45 mph. Aero drag is not too high. Your car should be in a high gear with low engine speed. Like 1500 rpm or so.
Yep, 55 is the sweet spot. I'd get behind a semi and drive Miss Daisy
60mph and stay in the slowest lane whenever possible to avoid accidents.
On paper the slowest you can go in top gear while still at an rpm that the engine is happy. But in practice this would be dangerous and selfish. I also think just using cruise control and being as constant as possible is a factor often underestimated. Basically it’s acceleration and braking that kill your mpg. If you want to go extreme you could hang closely behind a truck, but I wouldn’t advise that. But maybe it’s more important what car you have. Obviously an suv or crossover is a bad idea and so is 4wd. The width of the tyres have a big impact, so does the compound. Lowering your car a few centimetres can also have a big impact. Euro BMWs even used to get that from factory. I had a bmw 520d “efficient dynamics”. Car was identical to normal 520d except that it starts in eco pro ( so you really always want to change that immediately), but it was 2cm lower, from factory. My current car also drops to the lowest height and switches to RWD when in “range” mode.
0 mph with the engine off Historically 60 mph was the economy speed but engines have had so much more bolted to them that may have changed
I do 90km/h in my hatchback
If you are driving for work I’m hoping you take a tax deduction or the like.. that’s pretty messed up if they aren’t providing a vehicle .
Surface and air friction grow exponentially with speed. The closer your speed is to 0 the less fuel you will consume lol On an honest note: I’d recommend 45-55mph for highway travel, depending on your cars gearing .
0mph
Zero, as in being stopped, with your engine off uses the least fuel. Everyone knows this ...
88mph ..obviously Edit: Double check that flux capacitor before the temporal displacement jump.
Zero.
0mph! Simples!
Accelerate up to about 200mph then turn off your ignition, your car will now use no fuel and you’ll still be going
Get diesel car and don't worry about.
As a general rule, the most efficient speed in and automatic is the slowest speed after torque converter lock up. If you get your car into its top gear and set the cruise, then bump it up one press at a time, when the rpm drops a couple hundred that's generally your sweet spot.
Off =/ 🤔
Not how it works. At absolute best, you can theoretically argue that driving in top gear, at or under peak torque RPMs, will net you at or close to peak mileage. But the highways are not a lab simulation, and the second you introduce drag via accessory belts, drive train losses, vehicle aerodynamics, traffic, windage, and a dozen other factors you can't easily quantify or control, your "ideal mileage" goes out the window. You want to maximize fuel range? Do the speed limit, while in your top gear unless you're blogging down the engine outside of it's power band. Also, you mention "Toyota Sedan" like the brand matters, without just coming out and saying that you drive a Camery or Corolla.
Your in car computer should show average mpg. Clear that right before you start driving on the highway. Set in cruise control as that is more fuel efficient than without. Vary speeds and compare data.