Navistar this week unveiled its newest hybrid truck, the International WorkStar Hybrid 4x4, which the company says is the industry's first four-wheel drive diesel-electric hybrid commercial truck.

The International WorkStar Hybrid 4x4, part of the International severe service line-up of trucks for heavier duty applications, adds to Navistar's line-up of diesel-electric hybrid vehicles. (Navistar also produces the medium-duty International DuraStar Hybrid as well as IC Bus brand diesel-electric hybrid passenger buses.)

The International WorkStar Hybrid 4x4 can provide fuel savings of nearly 60 percent in utility-type applications when the engine often can be shut off, but electric power still operates the vehicle. Beyond the fuel savings potential, the WorkStar Hybrid 4x4 produces zero emissions when auxiliary equipment (like an overhead utility bucket) operates solely on the truck's hybrid battery power. The four-wheel drive capability of the truck is ideal for customers like utility companies, who need a truck to operate in off-highway conditions but are also looking to save energy and project a green image.

The International line-up of hybrid commercial trucks uses a mild parallel-type, diesel-electric hybrid architecture, developed by Eaton. The hybrid-electric system uses a regenerative braking system to recover energy normally lost during braking, stores the energy in batteries and adds power back into the driveline during starts and acceleration.

This capability makes the truck more efficient in standard driving, particularly in city and stop-and-go driving. When the truck reaches a work site, the hybrid system can power booms, aerial devices and other tools needed at the location for up to 90 minutes without the engine running, significantly reducing noise, emissions and fuel costs.