running a car completely with water
Cars can be run completely on water, but the systems involved are complicated. Despite this fact you see a lot of information on the Internet about how you can run your car on water 100%. You shouldn’t read such material as the methods involved are usually more expensive than any gains you would hope to make from the process. Some of these methods are not only expensive but rather unreliable as well.
The technology which is ridiculously cheap and which works best for most people is that technology which advocates a certain ratio of water for gasoline and uses the electrolysis process to convert water into HHO gas in order to provide a source of fuel.