Air-conditioning uses engine power and therefore fuel – so make sure it's turned off unless you really need it.



The general consensus is it's more efficient to drive with the windows down and the air-con off at lower speeds, but at higher speeds it's better to use the air-con and keep windows up due to the extra drag caused by having windows down.

If you're not using your air-con, it's worth turning it on once in a while as not using it can mean it stops working. Also, don't leave the engine idling. Drive off as soon as you start up and switch off as soon as you reach your destination. Turn your engine off where possible, eg, in traffic or during big delays on motorways.