Does a car burn more fuel the faster it travels?

Question

and less fuel the slower it travels?

Answer 1

Yep,

A little thing called wind resistance increases as the car gets faster so you need more horse power to go faster. The engine also runs more efficiently in a higher gear so the most ecomical speed depending on the car and engine is usually between 40 and 55 miles per hour in top gear where wind restance hasn't built up to much and the engine is not having to labour to much!

Also friction from the tyres increases the faster you go. Ever wondered why your tyres are so hot after a long run!

Normally about 2000rpm in top gear is your most efficient!

Answer 2

The answer is usually yes the faster you drive the more fuel you burn. I have a 1956 Buick with a monster chev motor in it and an auxilliary overdrive and it, because of the way it is geared actually gets better mileage at 85 MPH than at 50, but that is the result of technology tricking the engine into thinking it is not doing much work. Check out gearvendors.com if you want, but the O/D unit alone will not do everything. Your transmission, rear gear and motor's power curve all come into play.

Answer 3

Yes, it does. Ignore the answers that only adress engine rpm. Under high load, the engine will labor and not necessarily turn at a high rpm, but will however consume a ton of fuel. The force required to push a car through air is actually proportional to the SQUARE of the velocity, so yes, speed is a huge factor. The guy that says is irrelevant does not know how engines work. Fuel consumption is not linear to the engine speed.

Answer 4

A car is not fuel efficient at around 0 to 10 miles (16 kilometres) an hour as it is pushing against gravity, but a standard car starts to burn a lot more fuel than it normally does per mile at around 60 miles (approx 100 kilometres) per hour due to wind resistance and engine efficiency of revs per minute in the engine.

Therefore the AA recommend that you try to stock to 60 mph on a motorway.

Answer 5

every car has a speed at which it is most efficient. generally doing below forty miles per hour and above fifty-five miles per hour is never efficient in any car. the quality of the fuel and the service intervals have something to do with it too. best speed is usually about 55mph i.e 90 km/h. also for cars that have different driving modes the driving mode matters a lot too.generally any speed above 90 km/h and you are wasting fuel

Answer 6

Ha, yes and no!

Doing 70mph in third gear will burn more fuel than 70mph in fifth.

But assuming you're staying in the same gear, yes, cruising at 80mph on the motorway uses more fuel than cruising at 60mph because of the increased drag.

Oddly enough, the exception to this rule is a Mazda RX-7. Curiously, it gets better economy driving at 80mph than it does at 50mph becuase of the engine design.

Answer 7

Speed is largely irrelevant.

The higher the RPM (revolutions per minute) of the engine, the more fuel is burned. The easiest way to save fuel is to keep the RPM as low as possible.

Answer 8

To a certain extent, yes. Vehicles are made to get the best mileage around 60 mph. A couple simple things to do to increase mileage are; keep tires at max allowable pressure, clean or replace air filter and fuel filter, accelerate at a moderate pace, not too fast or granny slow.

Answer 9

What a clever question. Basically the more you put your foot down on the accelerator, the more fuel you use but with gearing,
it means cruising at 55mph in fifth gear is the most efficient use of fuel and you are getting most miles per gallon.

Answer 10

It ain't so much speed, it's more how hard the engine's working. Best "economy" is at that engine's peak torque rpm - probably around 50/60mph in top.
After all, if you went around with your foot flat to the floor in first, you'd be using a hell of a lot of fuel but not going very fast.