Is driving faster to one place more gas efficient or driving at a slower and constant speed?

lol the difference is minimal. but as you may be american, i will use an example… that massive road you have from 1 side to the other has a speed limit of 55mph. it is not incase you hit a tumbleweed, it is so you dont run out of fuel.

driving faster tends to need more revs, each rev requires a fuel ignition….. therefore driving faster uses more fuel! if you stopped driving, you would use NO fuel. so think about what ur saying and be less stupid!

EVERY CAR HAS THERE OWN OPTIMAL GAS LEVEL , AND TWO CARS OF SAME MAKE AND MODEL WILL DIFFER SLIGHTLY FROM ONE TO THE OTHER ,,, AND YES THE SLOWER CONSTANT SPEED IS BETTER ON FUEL ECONOMY , RUN AND GUN AS MOST CALL IT IS NOT ONLY BAD FOR FUEL CONSUMPTION BOR ALSO FOR ENGINE AND TRANSMISSION ALSO

thats is a commonly disputed question. it all depends on how much faster or how slow she will be driving. if she is driving 40mph at that same speed, vs driving 90 mph, driving faster will be more fuel efficient. if on the other hand it is a little bit faster as in, 35 mph as the slow speed, and 40 miles at the faster speed, i would recommend driving slower. the car will be running either way. if you drive fast you are burning gas but you will get there faster and would have not burned that much. if you drive slow, the speed wont burn as much gas but after a while, it is just a waste of fuel.

cruise control is a valuable and fuel efficient feature. you should tell her to use that.

every car does have an optimal mpg level

depending on your car, how you drive, and the road you drive on, it all varies.

every car does has its own most fuel efficient speed, its the highest speed on the highest gear with the lowest engine RPM. it can also be the highest speed on the highest gear but the speed you’re going has a lower engine rpm than the other regular speed, so if the engine rpm is 1950 at 60, but its only 2400 at 80, believe it or not, it would be more fuel efficient per mile to speed (80 mph) than go 60. When it comes to speeding, go at whatever max you’re capable of, the car is capable of, and you’re reaction speed is capable of. Fuel efficiency is the last thing on your mind if you’re not able to go faster safely, a danger to yourself and everyone else around you.

for most cars in the US, regular affordable cars, 50 to 70 is the most efficient speed. so if under 70 is “slower” then yeah, first try that. Carefully record your gas levels, distance traveled to find the average highway mpg. then later try faster (if you can do it safely, not all drivers or the vehicle can do that)

fuel efficiency also depends on driving habits, if you hold a constant speed (engine revving all the time) or sorta speed up and slowdown (like most people), you can waste more gas than if you find that perfect spot between speeding up and slowing down on the pedal and ‘just’ maintain that speed. doing that would make you go faster going downhill and slower uphills (even very slight slopes). Pedal work does have some influence on your highway mpg.

in conclusions, the vehicle’s mpg is pretty complicated. the variables: the vehicle design, the driver’s driving habits/style, engine speed, engine power, terrain. Basically try one method first, than another. do until you have found what is best in fuel and everything else. for now, slower is better, all cars have a engine break-in period of around 6000 miles. slower is better because the engine needs to be broken in first.