A/C on...windows up?

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My mileage does not change with or without AC usage. I get 22MPG with premium in a Subaru WRX wagon. I have learned full throttle disables the AC during acceleration
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No difference in instananeous mileage with A/C on or off.
No difference in Dragstrip times...

Chevy Avalanche.
I just let the climate control systems handle it.

I put windows up or down as I choose. Usually it's too noisy over about 30 mph.
 
Around town, unless it is extremely hot, I tend to run the air and have my window down. Freeway, have to keep the window up because of wind noise.
 
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Anyone painted their roof white, like they do on the school buses?




Interesting thought and a valid point. Dark colored vehicles DO experience solar 'heat gain' even on a cloudy day which leads to another question:

Do you 'vent'(windows down)your vehicle before running the A/C?
 
I open the moonroof when I first get in the car and turn on the A/C. This vents most of the hot air out of the car. I shut it after about 5 minutes.
 
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Quote:


Anyone painted their roof white, like they do on the school buses?




Interesting thought and a valid point. Dark colored vehicles DO experience solar 'heat gain' even on a cloudy day which leads to another question:

Do you 'vent'(windows down)your vehicle before running the A/C?




Find a black car and a white one parked in the sun beside one another for a significant time. Put your hand on one car and then the other. The black car will be significantly hotter.
 
Another way to keep cars cool and improve the acoustics a bit is a layer of thermal insulation between the headliner and the metal. Some have just a stiff material that doesn't insulate.
 
The funniest part about that Mythbusters episode was the reason they ran the windows up/down mileage test at 45mph: The oval track authorities believed running a Ford Exporer continuously at 55mph was unsafe. I can see their point. But since then, I lost all respect for Mythbusters results. Like Cartalk, they're entertainers first.
 
I tried this last summer on my 7-mile interstate drive. Once up to a set speed (70 I believe) I reset the gas mileage monitor on my Crown Vic LX. Doing this at various points throughout the summer in non-existent traffic I actually got better mileage with the windows UP and the A/C ON.

It's not the most scientific of tests, but I truly think the drag from the added wind resistance worsened my gas mileage than having the A/C on.
 
The initial load of the AC will be much greater than when the car interior cools. It will then cycle on less frequently.
So it depends on WHEN you make your comparisons/tests.
 
AC on has a much greater effect on an anemic 4 cyl car at hwy speeds than it does on a V8. The 4cyl is using all the torque it can muster just to go up hills on the hwy without downshifting. if you take away 10% of that available torque to drive the compressor with ~10 ft/lbs of torgue it becomes even more pathetic and mileage will begin to suffer. With a big V8 that produces around 3x the torque cruising on the hwy that same 10 ft/lbs is closer to 3% of the availablle torque which is incosequential. I guess the answwer to the original question is A/C on windows up with a big V8 and still get 28 mpg vs any 4 cyl that sucks to drive anyway unless its on a motorcycle.
 
454MAG, the lack of power from 4-cylinder engines, have been solved by the use of turbo or compressor. Or the use of BOTH turbo and compressor(the new VW golf GTI with only 1.4 liter displacement, and 170 horsepower and lots of torque from 1000rpm). The trend among engine designers today is downsizing AND increasing output.
 
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