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Does AC Use Gas In Your Car? Yes, Here’s How To Become More Efficient

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Key Takeaways

  • Running the air conditioner in gas-powered cars does consume fuel due to the engine powering the AC system.
  • Typically, running the car heater uses less gas than the air conditioner, but both have impacts.
  • Air conditioning can reduce fuel efficiency, potentially costing between one and four miles per gallon depending on usage.
  • For better fuel economy, use AC at high speeds, avoid excessive braking, and minimize idling.

Does AC Use Gas?

Yes, using the air conditioner in your car does consume gas. The AC system draws energy from the alternator, which is powered by the engine, and the engine uses fuel to operate.

vector graphic showing the answer to the question does ac use gas

How Much Gas Does AC Use?

Air conditioning will drop your miles per gallon only slightly when it doesn’t have to work too hard. When it’s very hot out, and the system is really cranking, it can cost you a few miles per gallon.

For example, in a recent study from Consumer Reports, they found that running the AC will cost you between one and four miles per gallon of gasoline.

Much of the variation in fuel consumption corresponds with changing ambient air temperatures. The hotter it is, the harder the system works, and the more gas you burn.

Using the AC Means Using More Gas

Using your car’s AC consumes gas, and in hotter conditions, can decrease miles per gallon by one to four, whereas the heating system, leveraging engine warmth, typically uses less fuel.

Which Uses More Gas: AC or Heat?

The heating system in your car uses the warmth of your running engine to create the hot air that eventually blows out of the vents on your dashboard and elsewhere.

It’s actually a bit more complicated than that, but the bottom line is that since the engine is already hot, it doesn’t take too much extra work from the engine to generate heat.

But, running the heater does require powering fans to circulate the air.

Those fans get their energy from the car, and that does mean using more gas than you would without the heater running at all. Typically, running the heat uses less gas than running the AC system.

How Does AC in Your Car Work?

A car’s AC system, similar to home units, uses a refrigerant, typically freon, which is compressed and flows through a condenser.

The cooling cycle involves the condenser coil dissipating heat from the refrigerant, an expansion valve reconverting it to gas, which then flows through an accumulator.

As warm air encounters the evaporator coil, it’s cooled and returned to the cabin, ensuring comfort and clear windshields.

Certified technicians should exclusively handle AC repairs, given their specialized nature.

Concerns like inadequate cooling or low freon in your car’s AC warrant professional attention. These techs offer services like refrigerant checks, compressor servicing, and addressing issues in the pressurized system.

Remember, air conditioning doesn’t just comfort you; it also ensures safe visibility by preventing windshield fogging.

How Does AC in an Electric Car Work?

Electric car AC systems draw energy directly from the battery, affecting mileage similar to gas-powered cars. Modern electric vehicles, like Teslas, often incorporate innovative designs, using desiccants and efficient, compact AC units.

These advancements aim for higher efficiency, breaking from traditional designs. While there’s no gas consumption, minimizing AC use conserves battery life. Additionally, electric cars typically have reliable AC units, reducing repair trips.

Battery Levels I’ve Noticed With AC Use

Where I live, the summers get very hot. During those times, I’ve noticed a massive drop in the battery levels of my Tesla when I use the AC to cool my car down.

A pet peeve of mine is touching a hot steering wheel or burning myself on the metal seatbelt buckle. So, I precondition my car.

It is during these times that I notice the biggest drops in battery levels.

Can Using Car AC Be Fuel Efficient?

Using the AC is sometimes more fuel-efficient than not running the system and opening the windows. According to the EPA, using your car’s AC can be more efficient while driving at highway speeds than having the windows open.

Open windows elevate aerodynamic drag, causing the engine to work harder and burn more fuel. That’s because when you open your windows, it changes the airflow over your car, letting air inside the cabin and creating drag.

That aerodynamic inefficiency will lower your fuel economy.

So, when you’re traveling at highway speed, say sixty miles per hour, or faster, it is more fuel-efficient to use your AC to cool off, as opposed to opening the windows and creating drag.

Is It Worth It to Use the AC?

For people who are sensitive to heat or have health conditions that make it harder to breathe in high humidity, running the AC is always worth it. But, there are some tradeoffs to consider.

Pros of Using AC

Keeps the temperature from becoming uncomfortably hot in the cabin

Prevents moisture from building up inside of the car when the fresh air is humid

Dries the air to limit condensation on the inside of the window

Preserves aerodynamics and limits air resistance of the car

Cons of Using AC

Can lead to condensation on the outside of the windows

Using the AC may negatively affect fuel mileage

Robs your car of some performance to provide cooled air

So, Is It Worth It to Run the AC?

In many cases, it is worth it to run the AC. It’s often good for you, your car, and your passengers.

On the flip side of that coin, cranking the air conditioner to the max fan and cooling settings when it’s not necessary, or using the AC when your car is idling, will both make it less and less worth it.

But, there are situations where it’s not worth it to run the air conditioner.

For instance, if you’re traveling slowly on a day when it’s quite warm, it may be advisable to open your windows instead. You won’t experience a major loss in fuel economy due to the aerodynamic drag of your open windows because you’re not going fast enough. Plus, since it’s very warm, your AC will have to work very hard.

So, enjoy the breeze with the windows down when you’re rolling slowly on a very warm day. Then, when you get up to highway speed, roll the windows up to retain your aerodynamic efficiency, and turn on the AC to keep comfortable.

Ways to Improve Your Fuel Efficiency

There are many tricks to improve your fuel efficiency that aren’t related to your air conditioner. By taking advantage of these techniques, you can probably offset any decrease in mileage created by running the AC.

Here are some major fuel savers that can boost your gas mileage significantly.

1. Use AC at High Speeds

Whenever you’re at high speed, leave the windows closed. Instead, utilize the air conditioner and maintain your aerodynamics.

2. Go Light on the Brakes

It’s good practice to only use the brakes when you need to slow down. Some drivers tend to be nervous on the brake pedal, tapping it more often than necessary.

By looking out far over the hood and well down the road, you can anticipate changes in the traffic pattern and prepare for slowdowns and stops by letting off the gas. Doing so preserves your momentum as much as possible, and going easy on the brakes improves your fuel economy.

Does free gas interest you?

During the research phase of this article, we found multiple ways to get free gas. The methods we found are not only easy, but have consistently worked for me time and time again.

3. Don’t Idle

Idling your car is a recipe for decreasing your fuel efficiency.

It consumes gas and accomplishes little. Especially when taking a wide perspective and considering how your habit over the long term affects your fuel economy, you should avoid idling whenever possible.

Wrapping Up

Now you know the facts. Running the AC does use up a bit of extra gas in a traditional car. Doing so in an electric vehicle also requires extra energy, running down the battery a bit faster.

So, you can become more efficient by limiting your use of the air conditioner in general, and only using it when you’re at a higher speed. Plus, you can improve your overall fuel economy by never idling and going easy on your brakes.

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