HHO kits are the systems for your car that converts water into HHO gas and adds it to the combustion process of the engine that way improving gasoline combustion for up to 50%, keeping the engine cooler and reducing carbon monoxide and carbon dioxide emissions from the engine. There are many people who say that you can't run your car on water and they are partially right. It is true, you can't run your car solely on water but you can make a HYBRID car out of it.