Furthermore, the cars are not plug-in hybrids, all electricity generation comes from regenerative braking.
What is regenerative braking? Never heard of this term before. If the electricity is generated while driving itself, then the need for an invertor is eliminated. Also, a cheaper battery will do the trick, instead of an expensive one made out of Lithium and Cobalt.
Regenerative braking uses the kinetic energy from the car to charge the battery. When you're not accelerating, the car uses the momentum already established to charge the batteries through a generator that's attached to the wheels (I believe). The end result is the car doesn't need to be plugged in. The result is the car slows down a bit faster when idling to a stop, nothing overly dramatic, but it's a far more efficient use of that energy, which in normal cars is jut wasted.