Hybrid electric vehicles (HEVs) combine the benefits of high fuel economy and low emissions with the power, range, and convenience of conventional diesel and gasoline fueling. HEV technologies also have potential to be combined with alternative fuels and fuel cells to provide additional benefits. Future offerings might also include plug-in hybrid electric vehicles.

HEVs typically combine the internal combustion engine of a conventional vehicle with the battery and electric motor of an electric vehicle. The combination offers low emissions, with the power, range, and convenient fueling of conventional (gasoline and diesel) vehicles-and HEVs never need to be plugged in.

How Hybrid Electric Vehicles Work

Hybrid electric vehicles are powered by two energy sources-an energy conversion unit (such as an internal combustion engine or fuel cell) and an energy storage device (such as batteries or ultracapacitors). The energy conversion unit can be powered by gasoline, diesel, compressed natural gas, hydrogen, or other fuels.

Hybrid electric vehicles have the potential to be two to three times more fuel-efficient than conventional vehicles. HEVs can have a parallel design, a series design, or a combination of the two.

The DoE Alternative Fuels and Advanced Data Center has animation showing how HEVs work.

Are There Tax Incentives for HEVs?

Yes! Visit the AFDC’s HEV Incentives and Laws page for information on state and federal incentives available for hybrid electric vehicles, and other alternative fuel vehicles and equipment.

Where Can I Get More Information?

The AFDC’s HEV Cost Calculator allows fleets to compare the costs, benefits, and emissions of hybrid electric vehicles (HEV) with those of conventional vehicles in two ways:

  • Single Vehicle Tool: Users can select one HEV and one conventional vehicle for comparison. Factoring in purchase price, fuel costs, repair and maintenance costs, resale value, and applicable tax incentives, the tool calculates expected lifetime costs for both vehicles, as well as cost and emissions savings associated with purchasing the HEV.
  • Fleet Tool: Users can compare two fleets of up to five vehicles-one composed of HEVs and the other made up of conventional vehicles. The tool calculates lifetime costs and emissions for each vehicle fleet.


  • See current available HEVs here.