Which is the Most Fuel Efficient, Air Con or Open Window?

Which is the Most Fuel Efficient, Air Con or Open Window?


Many people love to enjoy the summer breeze by driving along with the car windows down but is it better for your wallet to close up the windows and switch on the air con? Since summer is usually the time when people tend to go away holiday, and this, in turn, increases petrol prices, it’s a good idea to know which option can save you money at the pump.


Windows Down Causes Air resistance

Cars encounter air resistance (a.k.a drag) when moving through the air at any speed. These days most modern cars are relatively dynamic and are designed to pass through the air with hardly any resistance. But if a car has its windows down air passes into the car rather than flowing over it, causing the engine to work harder and use more fuel to move forward.

But does drag affect a car’s fuel economy more than air conditioning?

The short answer is yes. At certain speeds driving with the windows up and the air conditioning on is generally more fuel efficient for your car. Studies have shown that if you’re driving at around 80 kms per hour with the windows down, fuel efficiency is decreased by over 20 percent.

And while air conditioning also decreases fuel efficiency at that speed it’s by a significantly lesser amount, around 10 percent.

When to Use Air Conditioning

Even though using air conditioning is typically more cost effective for travelling at higher speeds, this works on the premise of your car having an efficient air conditioning system. If it’s an older model, then it will chew through the petrol just as fast as having the windows down.

However, those who like to cruise around town with the windows rolled down will be pleased to know that for travelling at speeds of around 60 km per hour or less, this is actually considered a more fuel efficient option. This is because there is less drag on the vehicle, and less stress on the engine when you’re driving at slower speeds.

So if you’re wanting to reduce your fuel consumption both for your wallet and for the environment then a combination of windows down and air conditioning use is best. You just need to be mindful of when to use either option depending on the speed you’re travelling at.