There seem to be a couple of misconceptions in this thread...
1) The car does not run on Hydrogen.
It runs on regular petrol/gasoline. It uses a hydrogen booster that converts water on-demand to a hydrogen/Oxygen gas mixture that is injected into the intake that catalyses the burn increasing the amount of fuel combusted. This increases efficiency. Another company doing a lot of work in this area is Ronn Motors
The Limited Edition Scorpion HX?
2) There is overwhelming anecdotal evidence of "water-power" being feasible
Inefficiencies of electrolysis is one of the reasons that hydro-boosters are used rather than trying to fuel the car entirely on hydrogen... But there are those that have allegedly discovered more efficient means using electrical pulses that "fracture" the molecular bonds reportedly by amplifying the resonation of the molecules until they separate. Google people like Stan Meyer and Denny Klien to find out more.
Meyer's design of the 90s successfully produced enough Hydrogen on demand to entirely power a car. He was repeatedly refused a patent on the grounds that it broke laws of physics until he took the device into the patent office and switched it on. The patent was issued. His device is covered in this 1990s episode of respected British science programme Equinox:
Stan Meyer - It Runs On Water ( Full ) Hydrogen Oxygen ( HHO ) - Zero Point Energy
Meyer miniaturised his device into a prototype that could be fitted to most road cars. He died months before taking it from prototype to production, soon after he had alleged that he had refused billions offered by oil consortiums for his design. Conspiracy theories are rife of course... I prefer to stick to the facts rather than speculate on any unproven relationships between events and his untimely death. Meyer was very untrusting and highly secretive, no one was able to reproduce his results because no one knew all the details of the design. A growing community is getting closer to achieving the same results since his patent expired. One place to start is here:
YouTube - ZeroFossilFuel's Channel