[Photo:Prius hybrid vehicle] A hybrid vehicle uses multiple energy sources or propulsion systems to provide motive power. This most commonly refers to gasoline-electric hybrid vehicles, which use gasoline (petrol) and electric batteries for the energy used to power internal-combustion engines (ICEs) and electric motors. These powerplants are usually relatively small and would be considered "underpowered" by themselves, but they can provide a normal driving experience when used in combination during acceleration and other maneuvers that require greater power. Modern mass-produced hybrids can recharge their batteries while underway. When cruising or idling, some of the output of the combustion engine is fed to a generator (sometimes merely the main electric motor running backwards) wh...more >>ich generates electricity to charge the batteries. This contrasts with all-electric cars which use batteries charged by an external source. Hybrids still require conventional fuel—usually gasoline, though diesel and other fuels have also seen occasional use.