That's going to be one huge bang when the tank ruptures in an accident (fiberglass?) ... if you want to run off of expanding gas then you can always go back to the Stanley Steamer ,,, water expands 1600x when going to steam ... I just don't see how that amount of energy can be stored with just compression into the tanks at no more than 120 psi (remember they said you can "recharge" at a standard tire fill at a gas station) ..
Yes, they said you could refill from a gas station's compressed air source. But they didn't say you wouldn't also be using the car's own battery or a plug-in at the gas station to run the air-motor in compressor mode.
Just sucking in ambient air and compressing it within the car takes 3-4 hours, but it takes 2 minutes if the air you are starting out with is already at 120psi. Because it requires less compression and cooling than ambient air would, that seems possible.
The car has a 5kw (7hp) electric motor to drive the air-motor as a compressor. If it can really fill the tank from 120psi to 4500psi in two minutes, it would only be using 160wh of electricity -- an amount easily drawn from an average-sized car battery.