Possibly impractical idea?

Question

For electric cars, why don't we have an electric motor, powered by batteries, each battery recharged by alternators in each wheel. As the wheel turns, the alternator generates power to charge the batteries, going down hills, the wheels turn without or at least with reduced assistance. Also, regenerative braking. Everytime the brakes are applied, a generator that is embeded in the pad will turn. Obviously the brake generator pad will have to be replaced from time to time. Anyway, I just thought of it earlier and it seems so simple that I must be overlooking some glaring reason it won't work or someone would probably already be doing it. I'm not saying it would be perpetual motion, it would just be ultra energy efficient. So please, if there are any oversights I made that render this idea impractical, please let me know.

Answer 1

To generate energy an alternator does not run without effort. It produces a drag or resistance against the force which is turning it, i.e. the motor.

But yes, some energy could be recovered by braking and running downhill.

Answer 2

Current technologies in this field are not advanced enough and any energy regenerated from braking in a small vehicle such as a car would not be stored efficiently, although many companies are trying to improve this so that it will be viable in the future, some trains however, such as the virgin pendolino return energy to the mains when they brake, as it is returned to the mains through the overhead cables, and not to an on board battery it is much more efficient.

Answer 3

That is, in fact, how certain existing hybrid motors work. The act of braking recovers some of the kinetic energy to recharge the batteries.