why does turning off the a/c make a car get better gas mileage?
2007-08-29 06:18:50 · 24 answers · asked by Wiseguy 3 in Cars & Transportation ➔ Maintenance & Repairs
thats a myth. if u believe turning of the air and rolling down the window helps it does you waste same amount of gas.
2007-08-29 06:23:32 · answer #1 · answered by Anonymous · 3⤊ 1⤋
It doesn't.
The Mythbusters TV show even did a whole epsiode on it.
The theory is that if you open the car windows, the increased drag makes the engine propel the car more efficiently down the road than if you make the engine work hy drawing some of it's energy to run the AC (with the windows up).
Turns out that the draw from the AC unit is smaller than the disruption in the aerodynamics of windows-down driving. So the car gets better mileage with the AC ON.
The Mythbusters guys did the test with twin cars on a track and ran 'til the cars ran out of gas. The one with the AC on went much further.
2007-08-29 06:28:47 · answer #2 · answered by swimeveryday 4 · 2⤊ 0⤋
It doesn't always. It depends on the shape, size and weight of the vehicle. Even whether you drive with the windows up or down (like if you're a smoker and drive with the window cracked.)
For many cars, driving with the a/c off reduces gas usage by reducing the amount of work that the engine has to do. There is a belt on the engine that drives the a/c compressor. Compressing freon takes engery. Making the car move requires energy. Energy comes from burning gasoline.
For others, like many small pick up trucks, driving with the windows closed and the air conditioner on helps mileage because with the windows open, there is more drag on the car because the air can't flow smoothly around the body; it goes into the cab of the truck causing turbulence and so on causing the engine to have to work harder.
Hard work requires energy. Energy comes from gas burning.
Hope that helps.
2007-08-29 06:28:14 · answer #3 · answered by Anonymous · 2⤊ 0⤋
Turning off the A/C can improve your gas mileage slightly but it certainly isn't that much of a noticeable difference to be uncomfortable in your vehicle..the only time I can honestly say that turning off the a/c would help is if you're sitting in bumper to bumper traffic for prolonged periods of time...this might not save you lots of $$$ on gas...but it could prevent a engine overheat if your vehicle is an older model and it doesn't have a electric cooling fan....stay cool and enjoy.
2007-08-29 06:34:34 · answer #4 · answered by flh_ryder 2 · 0⤊ 0⤋
It depends on how you frame the question. If you want to compare gas mileage running the A/C versus opening all the windows and creating drag, then the studies show it's a wash. You don't save money by turning off the A/C.
But if your question was if you will save money by turning off the A/C with your windows closed, then yes, you will get better gas mileage because the engine doesn't have to power the A/C compressor.
Rick
I'm a retired ASE Master/L-1 Technician. I still keep current with the latest automotive technology. Visit my blog for cool articles and TSB's: http://free-auto-repair-advice.blogspot.com
2007-08-29 06:28:53 · answer #5 · answered by Anonymous · 1⤊ 1⤋
The engine has to work harder to run the air conditioning compressor, which burns more gas.
If you drive a fairly new (aerodynamic) car, it's better to have the a/c on if your on the freeway, because having your windows down creates drag.
I drive a 1973 Buick with a Chevy 350, and I get great gas miliege, because I have no air conditioner. My husband drives a 1972 Chevy with a 350 with air, and he gets 3/4 of the gas miliege I do.
2007-08-29 06:28:18 · answer #6 · answered by Sondra 1 · 2⤊ 0⤋
It takes power from the engine to run the AC compressor. Try this - on a straight, level section of road, turn the cruise control on. Then watch the tachometer, as you turn the AC on, then off. You'll see the RPMs jump when you turn it on. The engine has to work harder to make that power, so your mileage goes down.
However, modern cars are more aerodynamic with the windows up than down, and so you'll actually have worse mileage if you roll the windows down and turn the AC off, than you will with the AC on and the windows up. You can prove it to yourself the same way - set the cruise, and open and close the windows while turning the air on and off.
2007-08-29 06:25:16 · answer #7 · answered by Ralfcoder 7 · 5⤊ 1⤋
It does affect your gas mileage, running your AC compressor robs power from your engine.... if you dont believe it go for a 500 mile trip with the AC on, then turn around and come back with it off..... it makes a big difference.
2007-08-29 06:29:28 · answer #8 · answered by Stampy Skunk 6 · 1⤊ 0⤋
it does becuase your motor has got to work less as hard I have a 4 cylinder and you can tell a big difference in horsepower when my ac is off and just have vent on. I can actually ride in 6 gear but if ac is on I have to drive in 5 so I can make it up hills and I live in S GA so not any big hills. But it does make a little bit of difference not much but it does a little
2007-08-29 06:25:59 · answer #9 · answered by Dixie 1 · 2⤊ 0⤋
Turning off the A/C does not save gas. Your engine is not working any harder to support the a/c. The air runs off of the electronic mechanism which is powered by the battery. Your engine is not turning over any faster or working any harder, therefore it does not use more gas.
Now, keeping your RPMs lower & maintaining a constant speed will help you get better gas mileage. Hope this answers your question!!
2007-08-29 06:27:03 · answer #10 · answered by buckshotbullies 3 · 1⤊ 4⤋
They've done some tests on this & there's no definitive proof that running the a/c has any effect at all on your gas mileage.
2007-08-29 06:25:10 · answer #11 · answered by Eric C 6 · 2⤊ 1⤋