Ask NRMA: Air conditioning or windows down?

Car air conditioning button
Air con in car

Tips for economical driving and fuel saving methods have long been debated by motoring experts and day-to-day drivers. 

 While there are a few no-brainers such as keeping your vehicle light and going easy on the acceleration, working out which is the better option between using the air conditioning or keeping the windows down continues to divide opinions.

And with good reason.

There is simply no way to get an exact answer on which option saves more money unless you were to drive the exact same vehicle, at the same speed and in the same weather conditions. Aerodynamics differ greatly between vehicles, and this impacts the drag faced when driving with the windows down.

Each car will have a different air conditioning system too, so while one may cause car’s speed and fuel economy to rapidly diminish, a different and more modern vehicle may see far better results.

There’s also other factors that can come into play. High winds will create more drag and high temperatures will force your air conditioner to work harder to keep a cabin cool.

If your car air conditioning isn’t working as well as it has in the past, drop into your local certified mechanics, to diagnose or repair any issues with your vehicle’s air conditioning system, including a regas or replacing the cabin air filter if required.

“Sometimes it’s simply easier to wind the windows down, particularly during times of high and dry humidity,” says Matt from NRMA motoring advice. “It’s during these times that the a/c system fights an uphill battle to cool the cabin. This is due to minimised moisture within the atmosphere which the a/c condenser relies upon to cool the high pressure a/c gas as it charges through the system.”

Driver and passenger comfort need to be taken into account, and aside from the scenario above, there are undoubtedly times where air conditioning is an asset. Arriving to an interview or a date in a sweaty mess because you were too cheap to run the air conditioning isn’t going to do you any favours.

The opposite is also true from time to time. Are you really too precious to enjoy some fresh air coming in through the window? One of life’s great joys is the freedom of driving with the wind in one’s hair, although travelling down a freeway with the windows open and incessant sound of wind gusting by can be tiresome.

There’s even a select few that like to have their windows down while the air conditioning is running, but this is completely counterproductive from an economy perspective.

Perhaps it’s best to use a very basic rule of thumb. When travelling slowly (60km/h or less) it’s more economical to have your windows down. If, however, you’re at high speed (100km/h or more) the drag created by having your windows down is worse on your wallet than using your air conditioning.

Whichever you choose to do, please be patient and stay safe on the roads these summer holidays.

How do you like to stay cool when behind the wheel?

Have any more questions?

Feel free to contact our Motoring Advice team