Alternative Hybrid Technology

I was working in the shop today with pneumatic tools, and I was thinking. It doesn't take much to spark an intriguing thought and I began thinking about the power of the pnumatic motor in the drill I was using. Then I linked that to the concept behind regular hybrid motors that mate an electric motor with a gasoline engine. I thought about how difficult it would be to replace the electric motors in hybrid with pneumatic motors. The wheels began turning.

I came home and checked the internet, because I figured I wasn't the first person to think of this idea. That's when I stumbled across this web article.
The concept with this one is even easier than my idea. Here's some of the concept:

The normal combustion engine can be a simple four cylinder engine. During the charging stage, some of the cylinders can be switched from firing (to power the car) to compressing air (to charge the pneumatic system). This eliminates the need for a separate compressor. Then during the power stage that drives the car there are two options. Option one is to use the engine like any other car, the other is to use compressed air to assist. The pneumatic assistance can be done in different modes. One mode would be to use compressed air to pump all cylinders. This would be used after stopping at a light and without any gasoline. The other mode would only add compressed air to the firing cylinders when needed in the same way a turbo or supercharger would. This would greatly increase the power for each of the cylinders, thus reducing the need for a powerful inefficient motor. According to the website this alone would reduce fuel consumption by about 32%. The other thing that would be a major plus to this system is it's simplicity. Compared to a typical hybrid system this system would remove the electronic motor, the drive assembly, and the expensive batteries. The only new thing it would add would be a compression tank and an extra valve in each cylinder. I think it is simple enough that retrofitting an older car with this technology wouldn't be impossible for the average handy-man mechanic. It sounds like a job for my buddy Joey.