Vehicle Repair

Effects of Car AC on Fuel Efficiency

Effects of Car AC on Fuel Efficiency


Have you ever wondered how cranking up the AC in your car affects its fuel efficiency? It’s a question that many drivers ponder, especially during scorching summers or on long road trips.

In this blog, we analyze various factors, including driving speed, external temperature, and even the impact of open car windows on fuel consumption.

Fuel Efficiency and Driving Speed

Fuel Efficiency and Driving Speed

Highway Havoc: Fast and Fuelish

When it comes to driving speed and fuel efficiency, the relationship can be quite counterintuitive. At lower speeds, say around 30 to 40 miles per hour, using the car’s AC has a minimal impact on fuel consumption. However, once you hit the highway and start zooming at higher speeds, the story changes.

The 55 MPH Myth

Remember the 55 miles per hour (MPH) speed limit during the oil crisis of the 1970s? The intention was to conserve fuel, and surprisingly, the same principle still holds true to some extent today.

Driving at around 55 MPH with the AC on is more fuel-efficient than cruising at 70 MPH with the AC on.

The Science Behind It

At higher speeds, the car’s engine needs to work harder to counter air resistance, which leads to increased fuel consumption.

When you use the AC, it puts additional strain on the engine, further compounding the fuel efficiency challenge. It’s like running a race while carrying a heavy backpack – you get tired faster and expend more energy.

Battling the External Temperature

Battling the External Temperature

Hot Days, Hotter Engines

As the temperature rises, so does the temptation to crank up the AC to its maximum cooling capacity. But how does external temperature impact fuel efficiency?

When it’s blistering hot outside, your car’s interior can transform into a sweltering sauna. Turning on the AC helps to cool down the air inside the cabin, providing a much-needed respite from the heat. However, this cooling process comes at a cost.

The AC and Engine Relationship

Your car’s AC system is connected to the engine, and they have a symbiotic relationship. When you activate the AC, the engine has to work harder to power the compressor responsible for cooling the air.

The hotter it is outside, the more heat the engine must contend with, making it work even harder.

Finding the Balance

Interestingly, driving with the windows down on an extremely hot day isn’t a better solution either. Open windows increase aerodynamic drag, forcing the engine to work harder and reducing fuel efficiency.

It’s a catch-22 situation, and drivers often grapple with finding the right balance between comfort and fuel economy.

Read Also: Signs That Indicate Your Car AC Needs Repair

The Impact of Open Car Windows

Impact of Open Car Windows

Windows Down vs. AC On

Driving with the windows down may feel like a more natural way to cool off the cabin, but it comes with its own set of consequences.

Open windows create drag, increasing air resistance and causing the engine to work harder. As a result, fuel efficiency takes a hit.

AC or Windows? It Depends!

The decision to use the AC or roll down the windows depends on your driving speed. At lower speeds, say, during city driving or on local roads, rolling down the windows is generally more fuel-efficient than using the AC.

However, at highway speeds, the aerodynamic drag from open windows becomes more pronounced, making the AC a better option for fuel efficiency.

Hybrid Cars: The Sweet Spot

If you own a hybrid car, you’re in luck. Hybrids are designed to maximize fuel efficiency, and many models have advanced climate control systems that minimize the impact of the AC on overall energy consumption.


The effects of car AC on fuel efficiency are not as straightforward as we might think. So, next time you embark on a road trip under the scorching sun, remember to consider these factors and make informed decisions.

Car Recovery Service Dubai is helping people to solve their Car AC Repair and fuel efficiency issue. If your car AC is not performing well or not oil efficient. Contact us now; 971 505 073124.

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