Ac/windows open?

Question

What raises your miles per gallon, having the ac on or windows open?

Answer 1

it is better to use your A/C, windows down creates drag.  I get maybe 1 mpg better with no a/c with the windows up.  I use the A/C, it doesn't effect mpg enough in my opinion.

Answer 2

Windows open can create extra drag which decreases mpg a little, but it depends on the car design, how many windows are open, and what speed you're doing. In city driving it makes very little or even no difference..

A/C puts a direct load on the engine and definitely decreases mpg, on some cars by as much as 15%. If you're silly enough to run the A/C with the windows open then mpg suffers even more and the A/C itself is put under extreme load which will shorten it's lifespan.

So, for economy, open a window and only turn the A/C on when you have to, remembering to close all windows and to move the air control to recirculate the pre-cooled air.