Air conditioning and gasoline mileage

[wagonman76]

I would say it is not horsepower, but it depends on how much extra torque the engine has. My Chevy Celebrity is very torquey, and makes absolutely no difference in mileage whether or not the AC is on. I drive the same roads at the same speeds throughout the year, using the same gas stations, so Id say that is a fair comparison. Now if I had a vehicle that needed to downshift a lot to gain back that extra torque to keep moving on the same road conditions, it is going to cost some mileage.