Originally Posted by
JamesH
they did it on mythbusters and came to the conclusion that the a/c thing is pretty much a myth.
anything they say goes.
Regardless of what the Mythbusters say, the A/C compressor creates drag on the engine when the clutch is engaged. To get the best mileage, one would have to roll around with the windows up/cracked and the aircon turned off. Also, one would have to turn off all unnecessary electrical devices as that also creates a load.
But for most folks, just putting the proper amount of air in the tires would do more good than the A/C thing.