ATLANTA (Jan. 4) — United Parcel Service will test an engine that combines diesel and electric motor technologies and produces fewer emissions than conventional diesels.

The Hybrid Electric Vehicle (HEV) will use a modified T444E diesel built by Navistar International Corp. with electronics developed by Lockheed Martin Controls Systems, according to the Atlanta-based parcel-delivery company.

The diesel engine turns a generator to provide electrical energy for 23 batteries and the drive motor, which propels the vehicle at lower speeds. A process called regenerative braking uses the motor as a brake and recaptures the vehicle’s energy, which is then stored in the batteries for future use. The diesel engine powers the vehicle at higher speeds.

Interest in HEV technology was heightened last month when General Motors Corp. said it would develop transit buses powered by hybrid diesel-electric engines, with testing to begin later this year in New York. The buses will use 40% less fuel than their diesel-powered counterparts, GM said. Honda Motor Co. plans to sell a hybrid gasoline-electric passenger car in the U.S. next year, and Toyota Motor Corp. will offer a sedan with similar technology in 2000.

“HEV technology is of particular interest to UPS because of its potential to reduce vehicle emissions, economize on fuel in stop-and-go situations, and reduce maintenance requirements to the drivetrain,” said Mike Eskew, UPS senior vice president of engineering.

The HEV provides higher fuel economy and with its reduced emissions can meet the EPA’s certification as an Ultra-Low Vehicle Emissions (ULEV) vehicle using current diesel technology, Eskew said, adding that the HEV’s sealed electric motor and long-life batteries require no maintenance.

Starting early this year, UPS will test the vehicle over an 18-month period in Johnson City, N.Y., Atlanta, and Los Angeles, chosen because they represent three different climatic and environmental areas. The tests will solicit driver feedback, measure emissions, and examine fuel conservation, maintenance issues, speed, acceleration, and grade performances.

Currently, UPS has the largest private fleet of compressed natural gas (CNG) vehicles in North America, with more than 900 package delivery vehicles that operate in 16 cities.