Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
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Q. Does a car use more gasoline when you drive with the windows rolled down or the air conditioning turned on?
A. This is a question that has lost plenty of people a bet. “We’ve tested this at various temperatures with multiple vehicles,” says Jake Fisher, CR’s director of auto testing. “We found that on an 85-degree day, running the A/C can reduce fuel economy by 1 to 4 mpg, depending on the car. But air conditioning dehumidifies the car’s interior, which can help keep the driver alert and safe. We think that’s a worthwhile trade-off.”
Rolling down the windows doesn’t appear to put more drag on a car’s aerodynamics. “The effect of opening the windows at 65 mph did not measurably reduce fuel economy,” Fisher says.
More on Fuel Economy
Best & Worst Fuel Economy: Fuel Sippers and Guzzlers in All Vehicle Categories
Most Fuel-Efficient Cars
Fuel Economy Guide
Study Shows Top Tier Gasoline Worth the Extra Price
Why You Might Not Actually Need Premium Gas
Tips on How to Save Money on Gas
Editor’s Note: This article also appeared in the August 2017 issue of Consumer Reports magazine.
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