So far I think this is a very promising concept - I was always weary about electrical hybrids because of the use of rare earth metals and the environmental impact in some regions because of that. Putting some nitrogen tanks and mechanical/electronic bits in a car to achieve the same effect for city driving seems like a big winner - mass produced I'd think you could make those cars only minimally more expensive than normal gas powered ones. Electrical Hybrid car prices, meanwhile, don't seem to scale down much.