High speed=more energy

I feel that in a way when a car is being driven at higher speeds an imense amout of potential energy is bing put to waste. We should be harnesing this energy in some form of wind driven generator built into the engine compartment or body.
William S 12/08/2013
All you would do is take energy out of the moving vehicle and lower economy. Conservation of energy. All you'd do is add drag.