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Does using the car air conditioning churn fuel?

You’ve got minimal fuel in the tank and no petrol station in sight. It’s the middle of summer and you’re on your way to somewhere important. Do you turn the car air conditioning off, windows down and sweat it out or do you leave the air con on and hope you make it to a servo in time?

Using the car air conditioner increases fuel consumption by 10%. But before you turn the air con off, switch to au naturel and wind the windows down, you should know that driving with the windows down in some cases can increase fuel consumption even further. Another 10% to be exact.

Researchers found that driving over 80kms per hour with the windows down increases a modern cars fuel consumption by 20%.

Modern cars are relatively dynamic and are designed to pass through the air with hardly any resistance. But if windows are down the air will pass into the car rather than flowing over it. This creates aerodynamic drag, which causes the car’s engine to work harder resulting in an increase in fuel consumption.

So the verdict is – if driving 60kms or less around the coast, it’s more fuel economical to switch the AC off and cruise with the windows down. Over 80kms wind those windows up and crank the AC.

Top tips to maximise Car Air Conditioning cool.

As soon as you get in the car, open the windows to vent hot air.

Use the recirculation system to improve cold air flow.

Set the temperature to fully cold and using the fan to regulate air flow.


If you find that your car is taking a long time to cool down, there may be a problem with the system or it could be out of gas. Give us a call on 1300 car elec before the summer heat turns your car into a sweat box!

Has it been over 2 years since your last AC Service?