All these fuel from water ideas are a con in my view. What they are really making is a different kind of battery which you need to charge up. The con comes when you realise that you still need to have a real source of energy to make the "fuel" - just like you do when you charge a battery.

OK, the cars can use a liquid instead of a solid battery to provide power but the real source of the energy is elsewhere. You still need wind/solar/coal/oil/gas/nuclear etc to make it work.