What is the most fuel efficient speed to drive on the highway? 60, 50, 40 m/hr?

Question

I noticed there is mostly americans on this site but for the canadians would it be 100, 90, or 80 km/hr?

Answer 1

stick with 65, this is what i drive on the highways. any faster on my 94 corolla and my gas goes away quick!

Answer 2

True, this is a very complicated question, however someone above was pretty close to the rule of thumb when they said the slowest the car will go after it locks into its last gear (typically) or if it's a manual (as is my case) the slowest you can go in 5th/6th without bogging the motor (keeping it above 1k-1.5k rpms in torquey motors(trucks,etc), 1.5k-2k in peaky motors(smaller/sporty cars)).
If you drive a bus which pushes an enormous amount of air, it will probably be much slower, whether it's in a lower gear or not.
Obviously the worst mileage is obtained at 0mph because the motor is running and burning gas, but the vehilce is not moving, so it is getting 0 mpg.
You increase this to 5mph and your mpg shoots up and with every mph keeps increasing (assuming either you or your trans. is shifting gears appropriately) until the efficiency gains your motor is obtaining is outweighed by the exponential increase in counterfources working on your car, such as friction (tires, belts driving auxiliaries, bearings, transmission heat, etc.) and, most importantantly air drag. The more aerodynamic the car, the faster it can go (all other friction/resistance factors being equal) before it's mpg curve peaks and dives.

I drive a Mitsubishi Montero Sport with a terrible coeffecient of drag (upwards of .40 or so compared to .25-.32 for efficiently shaped cars) and I get about 18mpg at 70mph, and about 23mpg at 50mph. That's almost a 30% improvement with a 20mph decrease. I could maybe get better MPG by going a little slower, but that's no longer HWY speed. Most car's optimal speed is between 45 & 55mph... I wish it were higher!

Answer 3

Why would it matter where you lived? The most fuel efficient speed used to be 55 mph. That is why the US interstate highways all adopted a 55 mph speed limit during the as crisis in teh ate 1970s. I would have to assume that the best speed would be a bit faster now because cars have advanced so much ni aerodynamics and engine efficiency. I would guess that new model cars would do best around 60 - 65 mph.

Answer 4

50 would be extra effective than 60. the reason fifty 5 replace into the extensive sort chosen interior the 70's for the national velocity cut back replace into using on-highway heavy accountability autos. After lots attempting out it replace into got here across that 55mph replace into the desirable velocity,any decrease and the engine, in maximum situations,would pass right into a lug condition which isn't gasoline effective in any respect. examine have at the instant shown that the desirable layout for a huge truck isn't the aerodynamic "anteater layout" particularly a flat-nosed cab-over layout with a windshield laid returned at an 18 deg. attitude. The "anteater" layout,mutually as aesthetically eye-catching, has too many aspects that advance the coefficient of drag previous practicality. A automobile vacationing lots under 50 will oftentimes not see lots extra earnings because of the fact of different aspects as properly wind drag.

Answer 5

I own a 1999 Ford Expedition when I am driving at 55 my RPM's are at 1500 that is just 700RPM's over idle I get my best fuel economy 18MPG.
It also depends on the maintenance and mileage if it is a diesel, brand new diesels get bad mileage 13MPG but as they break in there mileage goes up to 15-20 MPG or so.

Answer 6

When the tranny goes into O/D and the converter locks is the best speed for fuel mileage. On MY car, that's 46 MPH.

This is too slow for the interstate, so I'm forced to go 55, but my V8 STILL gets 22 MPG at 55, so I'm not complaining.

Answer 7

Depends on the size of the engine to be honest.

On a petrol car (gas) I would think around 2000RPM in the highest gear possible, now since every car is different with different engine sizes, this varies on the speed that the vehicle can do at this engine speed, it's to do with the engine size and the gearing

Answer 8

depends on the car and the road, but I believe that generally 60 mph gives you the best fuel economy. i used to prefer the 70 mph roads b/c i thought that the faster i went, the better economy i got, but i recently heard that this is not true.

Answer 9

It depends on your engine, gear ratio, and the aerodynamics of your vehicle. It's impossible to give a general answer that will be true across the board.

Answer 10

it would be around 60-80