The Hybrid Car misses the point...
The cars that run on water use a process of electrolysis to breakdown, or seperate, the Hydrodgen and oxygen, making HHO gas. A specific pulse frequency is acted upon a vessel of water. The vesse is much like a capacitor. The water is the electrolyte. The gas rises and is fed into a combustion engine. Apparently one developer died in the 1990's.
A simple application of this technology was packaged as a welder.
This stuff is starting to take off all over the place. I just hope that it becomes so common that my mechanic can set one up for me.