What Car? Q&A - Does air-con affect MPG?

Q: What effect does using air-conditioning have on a car’ fuel consumption?
Vince Earley

A: The air-conditioning system on a car is powered by a compressor, which, when switched on, places extra load on a car’ engine. This ultimately has a negative affect on the overall performance and efficiency. You can expect a 5-10% decrease in fuel consumption by switching the air conditioning system off.

Climate control systems in cars also include an air conditioner. These systems automatically vary the amount of air conditioning depending on specific temperature set by the driver. Should you have a car with climate control, pressing ‘econ’ should switch off the air conditioning compressor, allowing you to drive more economically.

Many car manufacturers recommend that you keep the air-conditioning system on constantly, even if you are not using it to produce cold air. By continually circulating the coolant within the system all the parts are kept lubricated and in working order.