The movable slats behind the BMW kidney grille can be closed, if necessary, to improve aerodynamics and bring the engine up to operating temperature more quickly. While driving, the air resistance of the radiator flow is at its highest, thus the fuel consumption is increased. The use of a variable air flap control allows the air resistance to be reduced by up to 10%, cutting down on fuel consumption. For this purpose, sensors measure the cooling requirements of the engine from all relevant data and decide to whether open or close the dampers behind the BMW kidney grille. The air flaps are then closed for normal driving as the engine requires a smaller cooling capacity. In addition to improved aerodynamic values, the engine reaches its operating temperature quicker, as no cold air can flow into the engine compartment. Therefore, both fuel and carbon emissions can be saved by shorter cold running phases. The air dampers only open when the full amount of cooling air is required, such as in traffic jams, high speeds, ascents or full operation of the air conditioner.