Do you believe that turning your a/c or heat off helps save gas mileage?

I always have the same gas mileage, whether or not I have my a/c or heat on. What do you think?

Do you believe that turning your a/c or heat off helps save gas mileage?
MythBusters did an episode testing this theory. It turns out that driving with the windows down wastes more gas than having the A/C on because it creates more drag and makes the car work harder. A/C does eat gas faster though. So, the best way to save gas is to have the windows up and the A/C off altogether.
Reply:Yessssssss.
Reply:Not running the A/C will save on gas mileage. But the heater doesn't operate the same way the A/C does the heat comes from the engine so its free compared to using more gas for the air.
Reply:If you are at above 55 mph or so, turning on the AC or heat will use more gas than leaving the windows down. If you are at below that speed, vice versa.
Reply:TURNING OFF THE A/C DOES SAVE GAS
Reply:your a/c yes. but not your heater it has not a thing to do with gas mileage. turn the heater on will help it from getting to hot if your motor is running hot.
Reply:Anytime the engine driven compressor is on it will make the engine work harder by putting more load on it. So yes having the ac on will reduce your mileage.