Does Running the Air Conditioner in Your Vehicle Waste Gas?

Running the air conditioner in a vehicle in hot weather reduces fuel economy and wastes gas, according to the U.S. Department of Energy. It estimates that running an air conditioner can reduce a vehicle's fuel economy by more than 25 percent.

To minimize the amount of gas wasted by running the air conditioner or idling with the air conditioner running, the Department of Energy recommends only using air conditioning when driving on a highway, not running it more than is needed to cool down the cabin of the car, parking in the shade or using a sunshade to limit heat buildup in the car, and only using it after driving with the windows down for a short time.