When it’s hot, open the windows and turn on the air conditioning.

Even if it is very refreshing, it is very uneconomical to have the windows open and the air conditioning running at the same time: The least fuel is used by switching on the air conditioning and leaving the windows closed:

• Air conditioning on and windows open: In this case you use the most fuel. The cooling unit cools, but in vain (beyond an outside temperature of 24 degrees), since warm air constantly comes in from outside. The open windows create unnecessary air resistance in the vehicle.
• Windows open, air conditioning off: The wind is refreshing, the more windows are open, the higher the vehicle’s air resistance, because when the windows are open, the vehicle’s aerodynamic shape no longer exists. In city traffic, open windows hardly bring any cooling anyway.
• Air conditioning on, windows closed: the most comfortable and also most efficient Variant! With the windows closed, no warm air from outside gets into the vehicle, the interior stays cool. Information on the optimal setting of the automatic air conditioning can be found here.

[box type=“download“] It is most economical to keep all windows closed and turn on the air conditioning when it is very hot. The air resistance caused by open windows is about as high as the additional fuel consumption of the air conditioning.[/box]