Well theoreticly it is IMpossible that car would run on water alone. With a basic understandig of chemistry and physics this should be clear. First you need to break down Water
2 H2O -> 2 H2 + O2
Now you want to burn the H2 to get energy ... this is exactly the reverse step
2H2 + O2 -> 2 H20
If you could drive a car by this you would have invented an perpetual motion. Both steps loose some energy as heat, therefor it is impossible to get (equal or) more energy out of step 2 than you need for step 1. Fueling a car with Water alone does not work!
In the link it says something about adding Aluminium because it reduces water to hydrogen. Nice idea... guess it would actually work. Problem is that aluminium is much more expensive than oil. You can't find aluminium in pure, only aluminiumoxid or other derivates. To get pure aluminium (which is needed here) you need a lot of energy. In numbers: for the production for 1 liter aluminium you need the energy of 3,8 liter oil . Wouldn't be cheaper and would cause more CO2 than fueling on the oil directly.
I guess the only way to get rid of high fuel prices is to go by bike
