Ok I have a car that moves against the wind (powered by an anemometer). I have also calculated the maximum possible power that can be drawn from the wind at a certain wind velocity. What I need to do now is to determine the power output of the car at a certain wind speed. How can I do this? I assume I could do something with a slope, as potential energy is increased work is done but what about friction? Another solution might be letting the wheels drive a generator that then produces power. Thoughts?