Munich  – Keeping cool in summer has a price with a car air-conditioner system adding between five and eight euros (seven to eleven dollars) to the fuel bill, according to a test conducted by Germany’s motoring association ADAC.

Reducing the cabin temperature from 31 degrees Celsius down to 22 degrees Celsius adds between 2.47 and 4.14 litres per 100 kilometres, a three-minute test found.

But the figure varied according to the car model and driving conditions in the city and on the motorway.

Older and more simply constructed air conditioning systems always operate in the maximum fuel-guzzling mode. The more intelligent systems regulate the compressor automatically, thus saving fuel, the ADAC pointed out.

But motorists can do a lot themselves to reduce the fuel thirst of the air-conditioner by opening all doors and windows for one minute before driving off so that the hot air can escape. While driving all the windows and sunroof should be kept closed.

The ADAC also advises motorists that it is healthier not to have too big a difference between exterior and interior temperature. Most people find a temperature of between 21 and 23 degrees Celsius comfortable. (dpa)