Which saves more gas? When you use your cruise control or manually with the pedal?

Question

I was told that using my a/c on my car actually saves gas and you'll get better milage. This is because the "drag" on the car is less with the windows rolled up. SO since that is something I once believed, what is the scoop about using cruise or the pedal? I live in northeast Maine, and the roads are up. down, and around. Would like to know which to use to conserve and save gas. Thanks.
P.S. Is it REALLT true about the a/c, too? :)

Answer 1

Continual acceleration and braking will use gas faster than gentle acceleration and cruising, so I believe that using the cruise control will save fuel.

From traffic lights, gently accelerate (ie. no huge revs) and flick on the cruise when you get to your desired speed.
This will work even in stop/start driving around the city but is even better for long country driving.

As for the A/C saving fuel, it's an interesting question.
I would lean toward the idea that the A/C is using more fuel since it is adding extra load to the engine. I think with the windows cracked a few inches the drag increase would be minor. All four windows down fully and maybe the drag might play a part.

Cheers.

Answer 2

Generally cruise control helps gas milage, but because you're in a hilly area nearly all the time, I say no in your case. Cruise control is dumb, so it reacts by kicking in some throttle when you slow down slightly. When the hill continues or gets steeper, it kicks in more, then downshifts. A long enough hill and it keeps doing that.

If you didn't have on the cruise, you would naturally give the car some gas anticipating the hill. You could gain enough speed, and regulate the gas to maintain speed without downshifting as much, or without flooring it like the cruise control does. Mulitply that by cresting the hill, where the cruise control might be giving gas still to keep to the setting, but without it on, you would plan ahead some and know the car will start picking up speed by gravity alone.

I think MythBusters screwed up their experiment. They used a Ford Explorer. It has the aerodynamics of a barn door. With the windows up or down, it still had the aerodynamics of a barn door. They should have used a somewhat aerodynamic car, after all the car makers do pay attention to that for gas milage. I think it would have made a difference in milage disrupting the Cd of a more slippery car with the windows down.

Answer 3

I believe that there's a modicum of truth to the a/c thing, because if the option is having the windows down, then yes, you get a lot of drag and the car has to work harder to go the same speed as with the A/C.

Cruise control does save gas; but if you're dealing with windy up and down type roads, it's probably not practical. The amount of time you'd spend breaking to slow down for a curve and then speeding up again would probably negate any real benefits of cruise control. It's really evident on the highway.

Answer 4

A/C uses A LOT of gas ( do the test by using the a/c on one tank and not using it with an other tank). As for the cruise control...doesn't change anything because when you go up a hill, your RPM will go up anyway to keep the speed: you would have to press on gas too if you were on manual. To save gas, start slowly on corners. On highways, don't go over 65-70 miles/h. If you have the option between highway or through the city for the same destination, go on the highway. Don't believe the crap the other people said

Answer 5

C/c is better because you keep a consistent speed and theirs little need to accelerate, which is where you use more gas. Most cars maximum efficiency is around 65MPH meaning its using the least gas to go the fastest possible speed. And the A/c is true because if you going 50mph or faster with the windows down your creating more drag. But vehicles newer then 2001 don't rely on gas for A/c it runs off of you Alternator.

Answer 6

Using the A/c will use more gas.

As for Cruise verse manual, you will save gas using manual. This is due to the fact that when you accelerate you use more gas, with cruise control it is always accelerating and braking to try and maintain an exact speed set by you especially on hilly roads. another way to conserve petrol is to take of slowly, if you floor it to take off it will use more petrol than if you just ease off from a stop.

better yet if its possible take public transport

Answer 7

Cruise control saves gas

Answer 8

Using the cruise control hels to save some fuel, but the difference is insignificant. Check tires pressure, dirty air filter causes more fuel consumption. The A/C takes lots of power from the engine - if it's a small car with small engine diriving without A/C you will save more fuel. If it's bigger engine, the difference will be very small.

Answer 9

Well you should get better mileage from your cruise control. The computer has a better response to what the engine needs for power than you foot does. I am a former Maineiac, moved to California 15 years ago.

Answer 10

cruise control saves gas
using the air conditioner uses more gas, but in the summer who really cares, it's not like you can really see the difference