It's a "cool" concept, but it won't work out.
First off, it doesn't look like a car, people want something that looks like a car and this thing looks a bit stupid if you ask me.
Also, if I'm getting a car that gets 300 mpg, I'd like some storage space so that I can actually take it long distances, but this thing has next to no storage space.
Another company just trying to throw their name out there, then when they don't succeed because of their futuristic take on the world will just blame it on the oil companies.
EDIT:
Also, the whole "Green" car thing is a bit of a advertising ploy. Every car made today is made up of like 95% recycled materials