The case study highlights the joint venture by Freightliner Eaton Corp., and FedEx Express to build a fleet of delivery vans powered by environmentally friendly diesel-electric hybrids.

The hybrid powertrains are said to provide significant gains in fuel economy, reduction in emissions, as well as noise pollution and engine idling on utility work trucks and walk-in vans.

"We have been working on diesel-electric hybrid programs since 2001 and are pleased with our efforts so far in helping achieve better fuel economy for the delivery and utility markets," said Elmar Boeckenhoff, senior vice president of engineering and technology for Freightliner."

The Stanford case study, which was published earlier this year, details the history of FedEx Express's partnership with Freightliner, Eaton -- the key developers of the hybrid E700 FedEx Express truck.

The test vehicle reduced particulate matter emissions by 93 percent, oxides of nitrogen emissions by 54 percent and increased fuel efficiency by 45 percent.

Nearly 20 pilot vehicles were placed into operation in 2004 outfitted with Mercedes 900 engines.

The electric motor starts the vehicle in motion and the diesel engine provides torque as needed or when the system's batteries need to be recharged. The high-tech batteries capture and store energy during braking, providing a source of stored electrical power for the motor during future acceleration. All electric charging of the battery is provided by the hybrid electric powertrain, and no external electrical infrastructure, such as power cord or electrical outlet, is needed.

The Stanford University case study charts the history of the E700's development. The study quotes FedEx as saying the E700 could eventually replace the 30,000 W700 medium-duty trucks in the next 10 years.

"While our primary targets are walk-in vans, utility vehicles and potentially school buses, among other commercial vehicles, it's only a matter of time before hybrid technology makes it into the rest of our product line," says Boeckenhoff. "Our hybrid diesel-electric vehicles will influence even heavy-duty truck development."