GREENSBORO, N.C. — Volvo Trucks has developed a new powertrain package for its VN series tractors that allows the engine to run about 200 rpm slower than usual, reducing fuel consumption by as much as 3% compared to traditional powertrains.

The XE (exceptional efficiency) powertrain package uses a concept Volvo has dubbed ‘downspeeding’ to slow engine speed and improve fuel mileage.

The new offering is only available on Volvo VN trucks with Volvo engines and its I-Shift transmission. The XE13 package allows the engine to cruise at 1,150 rpm at 65 mph, which is about 200 rpm slower than the average truck sold today, Volvo claims.

“Historically, we’ve seen a slow progression toward a lower sweet spot, with the 1,300 to 1,500 rpm range as the current industry standard,” said Ed Saxman, Volvo Trucks product manager, powertrain. “The engine with the XE13 package has a sweet spot of 1,050 to 1,500 rpm. Customers gain about a 1.5% fuel efficiency improvement for every 100 rpm of downspeeding, so fleets that spec’ XE13 can expect up to a 3% improvement when compared to another overdrive transmission in a similar operation.”

The XE13 package is approved with weights up to 88,000 lbs and consists of: a Volvo D13 engine with 425 hp and 1,750 lb.-ft. of torque; a Volvo I-Shift overdrive transmission with 0.78:1 ratio; axle ratios of 2.64 to 2.69; and proprietary software that allows for seamless communication between the powertrain components.

“With the new package, the engine runs in its sweet spot at any given speed, never straying from its sweet spot at any point from zero through top speed,” Saxman added. “When cruising at speeds below 60 mph, the intelligent software is designed to prompt the I-Shift transmission to downshift only when necessary for maximum fuel efficiency.”

Ron Huibers, senior vice-president, sales and marketing with Volvo said fleets that spend considerable time cruising at highway speeds will benefit the most from the new package.

Volvo says the XE13 is the latest in a series of fuel economy improvements, including its move to SCR in 2010 and a new aerodynamic package introduced earlier this year, which have collectively improved fuel mileage by 8% compared to EPA07 Volvo trucks.

Truck News executive editor James Menzies was among the first to drive the XE13 package from Volvo. He’ll have a complete review in the November issues of Truck News and Truck West.