Does Car AC Use Gas?

Many people believe that using the AC in their car will cause them to use more gas. So if you’re looking for ways to save gas, you might find yourself wondering if this is true.

So, the question becomes, does car AC use gas? And if so, is it worth turning it off?

We’re here to set the record straight, and we will also highlight a few other ways to improve your fuel economy. So make sure to keep reading! Let’s get started.

Does Car AC Use Gas?

The answer is yes, your car AC does use gas while being used. This is because the air conditioner is powered by the alternator, and the alternator is in turn powered by the engine. So by using the car AC, you add a small load to the engine which increases gas usage.

But how much gas does AC use? Let’s find out!

How Much Gas Does AC use?

In most cases, consumers would not notice the extra gas consumption. But according to EPA, running your car’s AC is the main contributor to reduced fuel economy in hot weather and it can surprisingly reduce the fuel economy by more than 25% for conventional vehicles.

So, for example, for a car that gets about 50 MPG, a 25% reduced fuel economy equals a loss of 12.5 MPG, which seems like a lot.

EPA also mentions that hybrids, plug-in hybrids, and electric vehicles (EVs) may notice an even larger effect on a percentage basis.

However, the impact on fuel economy depends on several factors, such as the outdoor temperature, humidity, and the sun’s intensity. And for you to notice a drop in fuel economy of up to 25% or more, the conditions must be extremely hot.

Under hot but normal conditions, it is more likely you will see a 5 to 10 percent reduced fuel economy while driving with your AC running.

Does Driving Without AC Save You Gas?

As stated above, the car AC burns gas by adding a slight load to the engine. But it’s a bit more complicated to answer the question if driving without AC will save you gas.

First of all, it usually depends on your vehicle’s specific configuration and the type of AC compressor it uses.

And while driving with the AC turned off may save you some gas, there are a few factors that affect this, and the savings would likely not be enough, and most people wouldn’t even notice. Furthermore, the benefits of using your AC usually outweigh the costs.

What Wastes More Gas Windows or AC?

You may have been told you can turn off your car AC and instead drive with the windows open to save gas, which is partly true.

But according to EPA, this may only be true at lower speeds and it can actually be more efficient to use your car’s AC while driving at highway speed than leaving the windows open.

This is because the aerodynamic drag (wind resistance) increases when driving with windows open which mean the engine has to work harder to push your vehicle through the air, and the wind resistance grows the faster you drive.

But even at lower speeds, it might not be worth sweating it out, and heat can also make you uncomfortable, distracted, and an unsafe driver. And by now, you might realize it won’t save enough to make much difference. However, that is up to you to determine.

How to Improve Your Fuel Economy in Hot Weather

When it comes to your car’s air conditioning, you can do a few things to help reduce the load on your AC and engine in hot weather. Here are our best tips:

  • Drive with open windows at lower speeds and use the AC at highway speeds. But remember, you’ll be a safer driver if you’re cool and comfortable.
  • Don’t use the AC more than you need and don’t set the AC to “lower” temperatures than needed.
  • Make sure to park in the shade or use a car sunshade.
  • Don’t idle with AC running before driving.
  • Let hot air out of the cabin by driving with the windows down for a short time before using the AC.
  • Make sure you understand how the AC controls work and how to best use it for maximal efficiency (Most owner’s manuals explain this).
  • If you have a plug-in hybrid or electric car, then pre-cooling your car while still plugged in the charger is a good way to extend your vehicle’s range.

Other Ways to Get Better Gas Mileage

If you want to get the most out of every tank of gas, then your air conditioner isn’t the only culprit to consider. Fortunately, we have listed a few other tips for you to get better gas mileage:

Keep your tires inflated: This may seem like a no-brainer, but properly inflated tires can make a big difference when it comes to fuel economy. Check your tire pressure at least once a month and inflate them to the manufacturer’s recommended pressure levels. 

Avoid excessive idling: When you let your car idle for too long, you’re wasting gas unnecessarily. If you’re going to be stopped for more than 30 seconds or so, it’s best to turn off the engine until you’re ready to move again. 

Drive sensibly: Aggressive driving (speeding, hard braking, rapid acceleration, etc.) can negatively affect fuel economy between 15 and 30 percent at highway speeds and up to 40 percent in stop-and-go traffic, according to AAA. So it’s definitely something you should try to avoid doing.

Avoid carrying unnecessary weight in your car: According to Investopedia, as little as 100 pounds extra in your car can reduce gas mileage by up to 1 percent. That means taking out anything you don’t need, such as golf clubs, backpacks, or that old box of books you forgot in the trunk, can help you get better gas mileage.

Perform Regular Maintenance: Another way to improve your car’s fuel economy is by making sure it’s well-maintained. That means getting regular oil changes, changing filthy air filters, bad spark plugs, etc. By keeping your car in good condition, you can extend its life and improve its fuel economy at the same time. So make sure you maintain your vehicle according to the recommended service schedule, and some extra TLC will benefit you in the long run.

Final Thoughts

While it’s true that the car AC does use some gas, the slightly extra consumption will likely be small, and most people wouldn’t even notice. So with that said, it might not be worth turning your cabin into a sauna by turning off your AC.

Instead, if you want to save money at the pump but still want to enjoy the cool air, there are a few other things you can do to get better gas mileage which we list above. Put these tips into practice and enjoy the savings!

Photo of author

Rickard Cefalk

Rickard is the owner of and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.

Leave a Comment