Why It’s Important to Understand Fuel Economy in Hot Weather
While hot weather actually increases your fuel economy, trying to keep you and your passengers cool and comfortable with the AC can reduce it. The hot weather can cause your engine to warm up to an efficient temperature faster and the warm air causes less aerodynamic drag than cold air. BUT- Running your vehicle’s air conditioning is one of the biggest contributors to reduced fuel economy in the hot weather (U.S. Department of Energy).
Different factors such as humidity, temperature, and sun intensity also play a significant role in your fuel economy. A conventional vehicle’s fuel economy can be reduced more than 25% due to AC being used, especially during short trips under very hot weather conditions (U.S. Department of Energy). Hybrids, plug-in hybrids, and electric vehicles can all be affected larger due to AC use.
Driving under hot weather conditions with your windows down also can reduce your fuel economy. Having your windows open increase the aerodynamic drag, causing your vehicle to require more energy to push through the air.
To improve your fuel economy, consider using your AC only when you are traveling on the highway and rolling your windows down when you are traveling at lower speeds. Driving with the windows open for a short amount of time before using the AC will allow the hot air to pass out of the cabin. Also, keep an eye on your AC temperature. If it’s lower than you need it to be, increasing it will help your fuel economy too.
A lot of people like to have their AC running before driving to cool the vehicle down. Don’t do this! Turning your AC on after you begin to drive will actually cool the vehicle faster rather than trying to “cool it down”.
Another helpful tip to keep in mind is to try to park in the shade, if possible. This will help your cabin from getting too hot.
U.S. Department of Energy. Energy Efficiency & Renewable Energy. Fuel Economy in Hot Weather. June 22, 2017.