Does air conditioning affect your vehicle’s fuel efficiency?

With the recent heatwave we’d be very surprised it you told us that the air conditioning in your car hadn’t been cranked up to help keep you cool through it. Many of us actually keep it on even in warm – as opposed to heatwave hot – temperatures, partly to keep us cool and partly to stop some of the pollution from other vehicles from making its way into our car. That’s all great, but one question we get asked a lot is how air conditioning affects fuel efficiency. Here is what we know…

Open windows vs air conditioning

Almost everyone knows that having the windows open while driving will create some drag. This will mean that your car engine needs to work a little harder to compensate, which in turn means that it will consume more fuel.

When it comes to turning on the air conditioning instead, a similar thing happens. While the drag isn’t there, switching on something that puts more strain on the engine means that it is still working harder than it otherwise would to make up for that, thus using more fuel. Fuel consumption can go up by up to 10 per cent with the air conditioning on.

When should you use the air conditioning?

First of all, be aware that any car accessory, from the radio to the windscreen wipers and the lights – will drain your battery and require your engine to work harder. The more energy the accessory needs, the greater that drain and the harder the work required.

There is an ideal speed at which your fuel economy is not too badly affected. If you are travelling at speeds below 55mph then you are better off having the windows open. At speeds higher than this – for example, on motorways – you are better off closing the windows and turning on the air conditioning.

What can you do to minimise fuel consumption?

One of the reasons why air conditioning adds so much strain to your engine is because it is working to cool down a hot car. By taking short journeys – which are typically at a lower speed – we make more trips in hot cars that we do longer ones in a vehicle that has had the chance to cool down a little.

The quickest way of cooling your car without consuming too much extra fuel is to open the windows and raise the temperature to the low- to mid-20s. Hot air will be pushed out as the air conditioning gets going and will be replaced by cooler air. Once it starts to feel cooler, close the windows and turn the temperature down a little at a time until you are comfortable. Cranking the temperature to something resembling arctic conditions while your car is hot will only put more strain on the engine and drain your fuel tank much faster than it otherwise would.

Stay on top of your air conditioning maintenance and you will also maintain better fuel efficiency. Clogged filters and low refrigerant levels will result in a hotter car, poorer air conditioning and more money spent at the fuel pump than necessary.

For more tips and tricks on keeping a fuel efficient and cool vehicle during the summer or for an air conditioning inspection and service, get in touch with our Double Dee Autos team. Call us on 020 8460 3040 with any questions or to book in an appointment.