The problem is terminology; when you say zero energy, you mean a net zero draw from the energy grid. This is not only doable, but quite common; just not in DC. In CA, Ed Begley jr. has a tv show, web site & speaking tour around this very topic.
As for electric cars, where did you get one? The only approved electric was the EV1 which Chev withdrew about 15yrs ago. They are now promising to release the Volt in ’10 using LiIon batteries this time. The current state-of-the-art would seem to be hybrid using non-corn source E85