I was unable to figure out the exact math for how much energy is actually stored in this tank, and how it matches up with promised performance given reasonable losses. Anyone else want to give it a shot?

...Another issue might be engine corrosion. Using regular air there will be a constant condensation of moisture in the engine - promoting corrosion. Exhaust systems would need to be stainless steel. Engines would need to be aluminum or some other costlier metal to machine into a durable engine.

Regular internal combustion engines also generate moisture, also corrosive. I think this is an easily solvable problem.

The air tank also does seem like it poses potential severe rupture danger problems - overfilling the tank could prove fatal to the occupants or anyone nearby or simply destroy the tank and cost a fortune to replace.

Filament-wound tanks based on existing technology are very strong, and properly designed, very resistant to routine damage. A standard test involves firing bullets through pressurized tanks with no explosion. Standard safety valve and burst disk backups built into the design (like they are for every pressure vessel--by code) would prevent damage from overpressure.

It would get clobbered in an accident and likely fold like an accordion. However, I admire their innovative approach. Looking at the video of the car running and driving it looks like they may have some real harmonic resonance issues that need work. This means the car will likely ride like a mack truck and may be noisy as well. Ten years from now or if they really bust their tails and have enough support - five years - and they may have worked out the bugs to create a viable car for certain regions and which may meet some buyers needs.

These are indeed major issues. It doesn't matter how wonderful a car's propulsion system is if it's such a lemon that no one wants to drive it.

It's very interesting and has a lot of potential, if indeed they work out the likely numerous bugs and limitations.

Agreed.