A petroleum–electric hybrid vehicle (PEHV) is a vehicle using an on-board rechargeable energy storage system (RESS) and a fueled power source for vehicle propulsion. The different propulsion power systems may have common subsystems or components.
A hybrid vehicle provides better fuel economy than a conventional vehicle, because the engine is smaller and may be run at various speeds, providing more efficiency. Other techniques may be used to recover or reduce waste energy (such as regenerative braking and shutting down the combustion engine).
The term hybrid when used in relation with cars also has other uses. Before its modern meaning of hybrid propulsion, it was used in the United States to mean a vehicle of mixed national origin, generally a European car fitted with American mechanical components; this meaning has fallen out of use. In the import scene, hybrid often described an engine swap. Some have also called flexible-fuel vehicles hybrids, because they can use a mixture of different fuels—typically gasoline and ethanol alcohol fuel.
