The greatest misconception about hydrogen is that we are making fuel from water. It is NOT possible to generate hydrogen at a rate fast enough to be used as the primary fuel. This is entirely incorrect and if it were true, would violate several laws of physics.
Hydrogen assists the combustion process of the existing fuel. Although you will enjoy substantial fuel savings, you will still have to use a primary fuel.
Hydrogen generators use electricity to split the water (H2O) into its basic elements of oxygen and hydrogen. The generated hydrogen is then injected into the air stream of the vehicle to improve combustion efficiency and fuel economy.
In a standard engine, the combustion cycle is very fast: 0.007 seconds. Most of the fuel molecules are too large to burn completely in this extremely limited time. Hydrogen burns and travels through the combustion chamber 10X faster than a gasoline flame.
Hydrogen fills the space between fuel molecules and has the effect of making them closer together. The flame travels faster and the fuel is exposed to flame sooner and for a longer period of time. The result is a cleaner, more complete burn.
The science behind hydrogen injection has been well documented and understood. It has been known for over thirty years that the addition of hydrogen to fossil fuels, burned in internal combustion engines, will increase the efficiency of the engine.
This concept has been validated by a multitude of papers published by the Society of Automotive Engineers (SAE) as well as by NASA and other National Laboratories.
Direct from 1977 article by *NASA: