Plug-In Hybrid Cars vs Range Extender Vehicles

Range extender vehicles (REV), also referred to as extended range electric vehicles (EREV), are effectively battery electric vehicles (BEVs) with a small internal combustion engine that is used to generate additional electricity.

REVs are typically considered as either BEVs (by the previous definition) or plug-in hybrid electric vehicles (PHEVs) due to the inclusion of a gasoline-powered engine. What separates the engines in REVs from PHEVs, however, is that their purpose is to supply the traction battery and electric motor with power rather than propel the vehicle. When the battery charge in a REV is reduced to a certain level, the engine is turned on to power a generator that recharges the battery as you drive, thus powering the electric motor.

The entire reason for REVs is to banish "range anxiety" from existence. Small powerplants are used to extend the range of the electric vehicle. It can be a gas engine or even a fuel cell. The first modern range-extended vehicle was the Chevy Volt which used a gasoline engine to recharge its electric motor. The Cadillac ELR is similar to the Volt, just a lot more expensive. Its 17.1-kWh battery will take you 40 miles before its 84-horsepower 1.4-liter 4-cylinder gasoline-motor engages to recharge the batteries. Together, the Caddy's gasoline-assisted electric powertrain averages 32 miles per gallon combined.

Another example of a range extender car is the BMW i3 REx. The basic i3 is an all-electric car, while the i3 REx includes a small gas-powered extender engine. The most advanced version of an REV today is the Toyota MIrai which is a hydrogen fuel-cell vehicle. Instead of using a gas-powered range extender engine, its fuel-cell system can generate 153 horsepower which runs the electric motor and recharges the batteries.