SEATTLE – Kirkland-based Kenworth Truck, a subsidiary of Paccar, plans to begin full production of its T270 and T370 hybrid trucks in early September, according to These vehicles come with an electric motor that assists the main engine during acceleration and can capture the energy produced from braking, storing it in a battery for later use.

Kenworth chief engineer Mike Dozier said hybrids are ideally suited for such delivery fleets, because stop-and-go driving allows the electric motor to operate and recharge its batteries more frequently. Hybrid motors can also vastly reduce the fuel consumption of trucks with accessories that rely on the engine for power.

Atlanta-based Coca-Cola Enterprises bought 120 of the initial, limited-production Kenworth hybrids for its distribution fleet and began deploying them in April. Spokesman Fred Roselli said the trucks increased fuel efficiency by 32 percent while reducing emissions by 37 percent and adding luster to the company’s environmental reputation.

Seattle-based Dunn Lumber, a much smaller, family-run business, has been using a hybrid truck to deliver lumber in the metro area. With the latest version of the battery, the truck gets up to 10 miles a gallon, while a similar, diesel-only truck would get less than 6. At current diesel prices, the savings are impressive, especially since the company currently spends about $250,000 annually on fuel.

The trucks’ dashboard is equipped with a color screen that indicates when the vehicle is running on electric, the current battery charge, and what mileage the driver is getting out of the system.

Kenworth’s hybrid system, developed in partnership with components manufacturer Eaton, relies for power on lithium-ion batteries. In Kenworth’s models, the battery hangs from the underside of the truck, making it easier to cool off.

Buyers of the trucks can apply for federal tax credits of up to $12,000, depending on the model.

The company is studying how to apply the technology to heavy-duty trucks, the eighteen-wheelers that carry goods long distances at freeway speeds.