Hydrogen is a clean energy source that can be used to power vehicles, making them more environmentally friendly. There are several synonyms for the term "hydrogen vehicle," such as Fuel Cell Vehicle (FCV), Hydrogen Fuel Cell Electric Vehicle (FCEV), Hydrogen-Powered Vehicle, and Hydrogen-Electric Hybrid Vehicle. FCVs and FCEVs are widely used to refer to the vehicles that use hydrogen fuel cells to generate electricity to power electric motors. Hydrogen-Powered Vehicle, on the other hand, may refer to cars that use hydrogen to power their engines directly, like hydrogen internal combustion engines (HICEs). Lastly, Hydrogen-Electric Hybrid Vehicles may have a combination of hydrogen fuel cells and battery-electric powertrains for their propulsion.