There are two main kinds of Hydrogen Hybrid automobile. These are fuel cell vehicles and Hydrogen internal combustion engines, (HICE) like our first automobile "The Scorpion". Fuel cell vehicles are electric cars. Hydrogen is pumped into a tank in the car, just as gasoline. The hydrogen gas is then fed into the fuel cell where it is electrochemically converted into electricity--with no combustion, no moving parts and no emissions other than water vapor. The electricity is used to power the vehicle.

Hydrogen ICE vehicles use a regular combustion engine modified to use gaseous hydrogen instead of liquid gasoline (much like a natural gas vehicle is modified). They burn hydrogen or a combination of gasoline and hydrogen, but since there is no carbon in hydrogen, there are no or almost no CO2 emissions and only trace amounts of NOx (oxides of nitrogen). Hydrogen ICE vehicles are typically about 30-50% more efficient than comparable gasoline vehicles.