I know it's nit picky... but air is not the fuel for this car... Air is just the energy storage medium - the battery. The fuel will be whatever ultimately drives the compressor (gas, coal, hydro, etc.)... I hope it has regenerative braking
Also, NoCO2 - the 100mpg was just speculation by the article writer....
I am curious as to how they're keeping it from freezing. As the whole system does generate heat, I imagine that with proper controls that problem would be minimized. I'm also curious as to what pressures they're dealing with.