The combination of Volvo's I-Shift automated manual transmission and a Volvo D13 engine with the XE13 software allows the truck to cruise at 65 mph at just 1,150 rpm - about 200 rpm less than the average truck sold today. Volvo has upped the torque output on the D13 to 1,750 pounds-feet, which allows engine rpm to fall as low as 1,050 rpm before downshifting. The broader "sweet spot" (1,050-1,500 rpm) extends the cruise range of top gear, reduces the number of downshifts required on relatively flat terrain, and keeps the engine at peak efficiency through a wider range of road speed -- a concept Volvo calls "downspeeding."
"The result is a truck that will cruise about 90% of the interstate highways in America at a very efficient cruise speed with minimal gear changes on rolling and mildly hilly terrain," said Ed Saxman, Volvo Trucks product manager for powertrain. "The 200 rpm reduction in engine rpm at cruise and few gear changes will produce efficiency gains in the order of 3%."
The XE13 package is rated up to 80,000 pounds (GCWR) and includes the following components:
* Volvo D13 engine with 425 horsepower and 1750 pounds-feet of torque
* Volvo I-Shift overdrive transmission with a 0.78:1 ratio
* Axle ratios of 2.64 to 2.69
* Proprietary software that allows seamless communication between Volvo's integrated 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 said. "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. Like the song says, the I-Shift software knows when to hold 'em and knows when to fold 'em."
"Any fleet focused on spec'ing their trucks for maximum fuel efficiency can benefit from the XE13 package, but fleets spending considerable time cruising at highway speeds will see the greatest improvements," sai8d Ron Huibers, Volvo Trucks senior vice president - sales and marketing. "Our intelligent, integrated XE13 package delivers improved fuel efficiency without sacrificing drivability during steep mountain inclines or stop-and-go traffic."
The XE13 powertain package is the latest step in fuel efficiency for Volvo customers, who are already achieving up to 8% improvements in fuel efficiency over EPA '07 engines, according to the company. In November 2009, the launch of Volvo's EPA '10 certified No Regen engines with SCR technology gave customers a 5% boost. Volvo's powertrain enhancements and advanced aerodynamics announced at the 2011 Mid America Trucking Show deliver up to an additional 3%.
HDT Equipment Editor Jim Park drove a Volvo VN series tractor equipped with the XE13 powertrain package from Greensboro, N.C., to Hagerstown Md., and will have a report in an upcoming issue of the magazine.