I was looking at an electric turbine near Cleveland and I thought, "why couldn't an automotive design engineer come up with a similar roof wind generator, for say the new Nissan Leaf all electric car? What about electric generators on the wheels that charge the car batteries as it is driven. This could eliminate plugging the car in at night.

I am sure that this Idea falls into the catagory of a "perpetual motion" machine, but why can't this be done? Why can't they make a self -charging electric car that does not need an engine or electric charging source to replentish its batteries?