Do a google search "run your car on water".
yeah no. electrolysis is not fast enough. you have to start with bottled hydrogen. it doesn't get an truer. and if you were thinking about using a hydrogen fuel cell hear this. hydrogen fuel cells are great but the materials used to make the membrane that separates the protons from the electrons by allowing the protons to pass through and forcing the electrons to flow through the circuit thus doing whatever work you want them to do so they can return/re-bond with the protons (turn on a light or run a motor.. etc) cost wayyy to much for the general public at this time.