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Hybrids are more efficient than comparable conventional vehicles, especially in stop-and-go driving, due to the use of regenerative braking, electric motor drive/assist, and start/stop technologies. Still, much of the energy is lost to engine and driveline inefficiencies or used to power accessories. About 25%–40% of the energy from the fuel you put in a hybrid is used to move it down the road, depending on the type of driving.

Energy Losses and Gains for a Hybrid Vehicle for Combined City and Highway Driving

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Energy Losses and Gains for a Hybrid Vehicle for City, Highway, and Combined Driving

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Note: The figure is primarily showing losses, but the regenerative braking gains are shown below 0%, offsetting some of the above losses.

Fact #882 Dataset

Supporting Information

Energy Losses and Gains for a Hybrid Vehicle for City, Highway, and Combined Driving
 Types of Driving
CombinedCityHighway
Types of LossesEnergy Losses
Engine Losses65-69%66-72%63-66%
Parasitic Losses, e.g. water pump, alternator, etc.4-6%5-7%2-4%
Power to Wheels, dissipated as:27-38%25-40%29-36%
      Wind Resistance11-16%6-11%17-23%
      Rolling Resistance7-11%6-11%8-11%
      Braking9-13%13-20%3-4%
Drivetrain Losses3-5%3-5%3-5%
Idle Losses0%0%0%
Types of GainsEnergy Gains
Regenerative Braking5-9%8-14%2-4%

Source: U.S. Department of Energy and U.S. Environmental Protection Agency, Fuel Economy Guide website.

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