Cummins has taken a big step in its quest to develop a plug-in hybrid electric vehicle that combines optimal fuel efficiency with improved performance.

The company recently announced that it has begun development of a Class 6 truck with plug-in hybrid capability, a vehicle it says could boost fuel economy by 50%. The U.S. Department of Energy has helped fund the project with a $4.5 million grant.

Cummins’ ultimate goal is develop a hybrid truck that combines reduced fuel consumption with advanced drivability and performance in any types environmental conditions. The trucks will feature other state-of-the-art technologies such as electronic braking and intelligent transportation systems.

The project could have wide-ranging impact because Class 6 trucks are used in a variety of commercial applications. The Class 6 category includes trucks with a single rear axle and school buses. Because vehicles in this category tend to have subpar fuel economy, the development of a hybrid truck represents an important step on many levels, including environmental.

Fuel consumption will be reduced by the development of a range of drive cycles that are designed to meet the everyday needs of fleet operators.

Researchers are seeking to enhance the powertrain by choosing the best engine suited for use as an electric commercial extender. The engine will manage the charge level of the electric drive battery pack.

Cummins executive Wayne Eckerle said integration and control of the electrified powertrain with the proper engine is the key to developing a plug-in hybrid truck. Eckerle added that he hopes researchers can soon make these innovations commercially viable, which in turn would translate into substantial savings per vehicle on an annual basis.

Cummins hasn’t announced when it expects the hybrid trucks to be available. Other partners in the project include PACCAR, the National Renewable Energy Laboratory, and Ohio State University.