U.S. Department of Energy - Energy Efficiency and Renewable Energy
Alternative Fuels and Advanced Vehicles Data Center
Hybrid Electric Vehicle Parallel Design
A hybrid electric vehicle (HEV) with a parallel configuration has a direct mechanical connection between the hybrid power unit and the wheels, as in a conventional vehicle, but also has an electric motor that drives the wheels. For example, a parallel vehicle could use the power created by an internal combustion engine for highway driving while using both the engine and electric motor power for accelerating. Some benefits of a parallel configuration are:
- A smaller engine provides more efficient operation and therefore better fuel economy without sacrificing acceleration power. The vehicle has more power because both the engine and the motor supply power simultaneously.
- Most parallel vehicles do not need a separate generator because the motor regenerates the batteries.
- Power does not need to be redirected through the batteries and can therefore be more efficient.
To learn about a series configuration for hybrid electric vehicles, go to the HEV Series Design page.