The second law of thermodynamics killed his water fueled car. That law is often referred to as the "irreversibility of nature" or the law of increasing entropy.
Ive heard that it is through electrolysis/hydrolysis of water that his car is able to run.
Here are some equations:
2H2O → 2H2 + O2 [Electrolysis step]
2H2 + O2 → 2H2O [Combustion step]
Since the first reaction is the reverse of the other, it should follow the second law of thermodynamics that no process can be 100% reversible. Even with the assumption that the combustion of Hydrogen is 100% efficient (which in reality is up to 20% efficient only). Then it can be concluded that the energy required to drive the electrolysis is greater than the energy produced by the combustion of hydrogen.
Hmm.. his car is still running even with a deficit in energy. e
ither he has a hidden fuel tank or he must be going against the laws of thermodynamics...