On Earth Day, I saw a television spot for GM that showed their hybrid, electric and upcoming hydrogen-powered cars. Personally, I like the French car that runs on compressed air and can be filled within 3 minutes and, in emergencies, can even self-refuel.
But I share the same sentiments as the OP. No matter what powers the car, the fact that there will still be a million cars on the street is not a pleasing prospect. Motorists will still speed, pass recklessly and dangerously and crowd cyclists unnecessarily. Only now, they'll be environmentally less damaging.