Volvo says its cars are tested under the most extreme conditions found on this planet. In Arizona's blisteringly hot desert and in the biting cold of the Arctic north.

"Our cars have to be able to withstand ambient temperatures between -40 and +60 degrees C.

This requirement has been around a long time and is one effect of our safety tradition. Our aim is to create the best possible total function for all climates," says Jan Inge Eliasson, head of the Complete Vehicles Testing department at Volvo Cars.

The requirement applies to the entire car, down to the very smallest detail. A Volvo consists of about 40 main systems such as the engine, climate unit, seats and so on. These are divided into 400 subsystems such as the starter motor, fan, seat heaters and others. Which in turn consist of a total of about 3000 components - everything from sensors to heating circuits.

Systems and components must together guarantee thousands of different functions. For instance that the seat can be moved fore and aft, that the fan delivers the right power, that the windscreen wipers operate at their set intervals and so on.

In addition to these basic functions, the car also has a long list of attribute requirements to live up to. And it is here that the temperatures come into the picture. A requirement may read something like: "When starting at -20 degrees, it should take a fixed amount of minutes for the windscreen to be demisted", or "When driving at -15 degrees, there should be a certain specified difference in temperature between the head and feet".

"Extreme winter climate is probably the toughest test to which one can subject a car. The stresses on the engine, steering, climate unit and other systems are immense. As far as I know, we are alone in carrying out tests down to -40 degrees. The reason is our Scandinavian heritage.

Both we and our customers impose extra demands on us since we come from Sweden," relates Jan Inge Eliasson.