They may be small-battery 'mild' hybrids-with electric motors that add some acceleration, recover energy during braking, and provide some juice for stop-start systems-or big-battery, long-range EVs. These vehicles are largely defined by the amount of electric assist and electric-only range they provide. In addition to hybrids (HEVs) and plug-in hybrids (PHEVs), the universe of electrified vehicles (that is, vehicles that incorporate an electric motor into their powertrain) includes full-electric vehicles (EVs) that are powered solely by a large battery pack and have no gasoline engine. These share and sometimes trade off the job of delivering power to their drive wheels as needed to provide the best fuel efficiency in every driving condition-in the city, on the highway, and at varying speeds and rates of acceleration. Hybrid vehicles use a combination of gasoline-fueled engines and electric motors.

The word 'hybrid' means simply 'of mixed origin,' which perfectly describes both hybrid and plug-in-hybrid vehicles.