Hybrid electric vehicles (HEVs) are powered by an internal combustion engine (ICE) in combination with one or more electric motors that use energy stored in batteries. HEVs combine the benefits of good fuel economy and low tailpipe emissions with the power and range of conventional vehicles. The standard type of HEV cannot be plugged in and charged from an external source. Their batteries are charged as the vehicle brakes in a process known as recuperation or regenerative braking. This makes them more efficient as the energy recovered is normally lost as heat.
Examples include the Toyota Prius, Audi A3 Sportback and BMW 3 Series.