It is no accident that the most fuel efficient vehicles in some classes for this model year are hybrid-electric vehicles (HEVs). Hybrids combine the best features of the internal combustion engine with an electric motor, and they can be configured to achieve a variety of different objectives, such as improving fuel economy, boosting performance, or providing electrical power to auxiliary loads such as power tools.
HEVs are primarily propelled by an internal combustion engine, just like conventional vehicles. However, they also convert energy normally wasted during coasting and braking into electricity, which is stored in a battery until needed by the electric motor. The electric motor is used to assist the engine when accelerating or hill climbing and in low-speed driving conditions where internal combustion engines are least efficient. Some HEVs also automatically shut off the engine when the vehicle comes to a stop and restart it when the accelerator is pressed. This prevents wasted energy from idling.
Unlike all-electric vehicles, HEVs now being offered do not need to be plugged into an external source of electricity to be recharged; conventional gasoline and regenerative braking provide all the energy the vehicle needs.
The federal government is currently offering tax incentives for HEVs and other alternative fuel vehicles. Some states also offer incentives.