Nowadays optimizing the fluid dynamics of cars is a obligatory part of the developement of a car. The aim of this experiment is to deliver the basics for such technical processes. In the experiment the user can determine and compare air resistance and coefficient of air friction (cw-value) of different vehicles (sports car, offroad car, fire engine) in a wind tunnel. One can vary the velocity of the air flow and the size and profile of the vehicles hit by the air stream. At the end the user should be able to estimate the impact of air resistance during car driving on the consumption of gasoline i. e. what is the amount of energy required to overcome only this air resistance.