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How Much Does Using Your Car’s AC Affect the Fuel Economy?

It's summer again, and many people are turning on their air conditioning to stay cool. As expected, your car's air conditioning unit will have an impact on your gas usage and, thus, your fuel economy. Here's a look at just how much gas your car's AC uses and what you can do about it.

It’s summer again, and that means that many people are taking a vacation, and others are simply turning on their air conditioning to stay cool. However, just like a home AC unit, your car’s air conditioning unit will actually have an impact on your gas usage and, thus, your fuel economy. Here’s a look at just how much gas your car’s AC uses and what you can do about it.

Just how much gas your car’s AC uses

A car air conditioning control panel
Car Air Conditioning | Michal Fludra/NurPhoto via Getty Images

Like a home air conditioning unit, a car’s AC is a bunch of machines working together to cool you down. Since machines need power, it gets that power from your car. So, if you’re driving a gas-powered vehicle, that AC unit will ultimately get power from your engine burning through some gas. 

According to the EPA, a car’s AC unit can actually use quite a bit of fuel. However, it depends on a lot of factors. In the worst conditions, the EPA said that using the AC in your car can reduce your fuel economy by up to 25%. For a car that gets about 30 MPG, that’s equal to a loss of 7.5 MPG. An obvious solution may be to buy an EV. However, like the EPA notes, using the AC on an electric vehicle can also hurt its fuel economy by quite a bit.

Staying cool without an AC

Fortunately for budget-conscious drivers, windows do exist. Simply rolling down the windows and letting the breeze come in can cool you and your car down. With that being said, there’s a small problem with that advice. According to the EPA, rolling down the windows when driving on the highway will hurt your fuel economy, even compared to when using the AC. This is because of how aerodynamics work.

As such, the EPA’s advice is to roll down your windows at low speeds, while it may be better to bite the bullet and use the AC at highway speeds. However, that doesn’t mean that drivers need to use their AC at highway speeds. After all, there are other ways to stay cool without rolling down the windows.

For example, the Zebra wrote that one of the cheaper ways to stay cool is by getting a 12-volt portable fan that you can install on your dashboard or visor. Alternatively, you can also use windshield shades to block the sun from overheating the interior of your car. Other classic summer cooling techniques like drinking some cold water or sitting on a towel if your car has leather seats will also cool you down a bit.

Other ways to save gas

While some folks may want to turn off the AC to save a few bucks, other folks may not have a choice. Other techniques are used other than not using the AC if you need to conserve fuel for whatever reason. For example, driving at a steady pace below 50 MPH can dramatically improve your fuel economy, especially on highways. 

Other techniques are commonly used by folks who are called hypermilers. Hypermilers specialize in getting as much fuel economy out of their cars as possible, and their techniques work. For example, hypermilers will try to break as infrequently as possible. This is because it takes energy to slow the car down, so it will save fuel if your car is coasting for as long as possible. Obviously, however, this method isn’t as easy to do in the city compared to highways.


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