Two things that stuck out:

1. It is built in fibreglass to be very light. Good thing, but is really a seperate issue from the engine.

2. It runs on compressed air, which might be a better form of storing energy then a battery (I really do not know) but just as batteries or fuelcells it moves the energy 'production' from the car to another place. In itself probably a good thing, but that other place needs to be included in the energy calculation.