SEATTLE – Kenworth Truck Company and Dunn Lumber, two long-time Seattle-area companies, have teamed up to bring Kenworth’s first medium-duty hybrid-electric truck into the U.S. market.

Kenworth’s goal for its new medium-duty hybrid is to enhance fuel economy by up to 30 percent in start-and-stop applications, such as pickup, delivery, and utility trucks. Kenworth is offering limited production of medium-duty hybrid trucks for municipal fleets and utility companies this year with full-scale production expected in 2008.

Above 30 mph, the Kenworth hybrid operates like a standard diesel vehicle with all power coming from the engine during steady driving conditions. Below 30 mph, it uses a combination of diesel and electricity with the system automatically switching between the two modes of operation. Electricity generated through regenerative braking is stored and used for acceleration, assisting the diesel engine.

Dunn Lumber’s new Kenworth Class 7 hybrid, which can carry a payload of up to 16,000 lbs., features a PACCAR PX-6 240 hp engine, integral transmission-mounted motor/generator, frame-mounted 340-volt battery, and dedicated power management system.

The Dunn Lumber fleet includes four Kenworth T800 Class 8 trucks and six other Kenworth medium-duty conventionals that run between 20,000 to 26,000 miles annually.