CHICAGO. Navistar today unveiled its newest hybrid truck, the International WorkStar Hybrid 4x4—the industry’s first four-wheel drive diesel-electric hybrid commercial truck—along with the 2010 MaxxForce DT Advanced EGR mid-range diesel engine here at Work Truck Show and 45th annual convention of the National Truck Equipment Assn. (NTEA)

The WorkStar Hybrid 4x4 can provide dramatic fuel savings of nearly 60% in utility-type applications when the engine often can be shut off, but electric power still operates the vehicle, the OEM said. 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 Hybrid Truck Users Forum (HTUF), a national group of utility companies that own hybrid trucks, estimates that 1,000-1,500 gallons of fuel can be saved per utility truck annually. At the high diesel prices seen throughout most of 2008, that equates to a savings of $4,000-$6,000 in fuel per truck annually, according to the company. It also results in annual greenhouse gas reductions of 11 to 16.5 tons of carbon dioxide per unit.

The International line-up of hybrid commercial trucks uses a mild parallel-type, diesel-electric hybrid architecture, developed by Eaton Corporation, which leads to less diesel fuel use and fewer emissions. The hybrid-electric system utilizes 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.

To meet the U.S. Environmental Protection Agency (EPA) 2010 emissions requirements for on-highway diesel engines, MaxxForce Advanced EGR engines will use proven technologies such as advanced fuel injection, air management, electronic controls and proprietary combustion technology.

“We’ve been conducting rigorous testing and analysis in our engine labs and currently have 2010 prototype engines installed in medium- and heavy-duty test trucks,” said Ramin Younessi, group vp, truck and engine product development. “These test vehicles are on the road in real-world conditions and will log millions of miles of real-world experience before the launch of these engines.”

Other major truck and engine manufacturers are choosing a 2010 emissions path through selective catalytic reduction (SCR), which requires the use of an additional operating fluid, called urea, as well as significant aftertreatment equipment which will add hundreds of pounds to each vehicle.

Navistar’s EGR approach will not require the use of urea or the addition of heavy on-vehicle urea storage tanks, converters, heaters, and the additional electronics required by SCR systems.

“Many of the OEMs adopting the SCR strategy point to its use in Europe where emissions standards are not as stringent as the U.S.,” added Younessi. “However, at least two European engine manufacturers are adding a non-SCR solution to meet Europe’s next emissions hurdle. Also, three major U.S. companies have recently announced production plans for non-urea SCR systems, helping raise some serious doubts about the long-term viability of urea-based SCR.”