Higher MPG: Windows Down or Air Conditioning On?
Many drivers turn their air conditioners off as part of the ongoing effort to save gas. Before you join the growing number of motorists sweating out the summer months with car windows down or the masses that crank up the air conditioning without hesitation, pay attention to the healthy debate about which option saves the most gas.
Leaving Air Conditioning Off
Air conditioning has become standard equipment for most modern vehicles, but many complain about the extra load these devices represent. When drivers want to cool off, engines must work harder and consume more fuel. Thus, you might logically conclude that keeping the load off of your engine will help improve the fuel economy of your car. Automotive air conditioning units work efficiently, so you might not notice a difference in fuel consumption while operating your car in many conditions. Regardless, seasoned automotive engineers remind drivers that cooling a car requires a lot of energy. In the case of cars, that energy comes from gasoline.
Consumer Reports’s auto-test department performed a study that found air conditioners reduce fuel efficiency by up to 10 percent. High gas prices and long road trips can make drivers like you consider leaving the air conditioner off during the summer to save a substantial amount of gas. Before you lower your windows, you should understand that you could actually set the stage for higher fuel costs.
Rolling Windows Down
Open windows do not directly affect the performance of your engine, but they still affect fuel economy. Air flowing over your car gets sucked into your windows, creating a breeze. Unfortunately, the air flow creates resistance, increasing the work your engine must do to move your car down the road. Air resistance becomes a significant problem at high speeds. In fact, a Society of Automotive Engineers (SAE) study found that open windows reduce gas efficiency by 20 percent at 55 mph.
Understanding the Verdict
Drivers can benefit from using their air conditioners and from lowering their windows at different times while driving. Cars moving at high speeds experience increased air resistance, especially when they have open windows. Meanwhile, slow-moving cars do not meet substantial wind resistance, so drivers can lower their windows and expect to save fuel by turning off air conditioners. Some experts suggest that drivers can save fuel by opening windows at speeds below 40 mph. Cars driving faster than 40 mph will usually use less fuel with windows up and air conditioners on. Now, enjoy your summer and save gas by wisely using your car’s windows and air conditioning.