@Shenango, are you disagreeing that perpetual motion is not possible, or that friction is what ultimately makes it not possible. Yes, regenerative braking does work, and yes, when an electric car coasts downhill, the turning motion of the wheels does generate electricity to charge the batteries. However, I was agreeing with @diymirage when he said that an alternator placed on an electric car could not charge the batteries faster than the electric car's motor depleted them. That is true. And a car that could always keep its batteries charged would be displaying perpetual motion. That is not possible, and friction is the culprit. I took a lot of physics in college. I could dig out an old textbook if you like.