Volvo has brought an interesting idea to market -- cruising a heavy truck at just 1150 rpm. That's the new XE13 – denoting 'exceptional efficiency' – powertrain package that lowers engine rpm at a given road speed, a concept the company calls “downspeeding”. It combines the I-Shift automated manual transmission and a Volvo engine with modified software, allowing the engine to cruise at just 1150 rpm at 65 mph, which is about 200 rpm less than the industry norm.
 
Ed Saxman, Volvo's powertrain guru, says the XE13 package gives the engine a ‘sweet spot’ of 1050 to 1500 rpm. He adds that users gain about 1.5% fuel efficiency for every 100 rpm of downspeeding.
 
The XE13 package is rated for a GCWR up to 80,000 lb and includes, as well as the proprietary software, a Volvo D13 engine with 425 hp and 1750 lb ft of torque; Volvo I-Shift overdrive transmission with an 0.78:1 ratio; and axle ratios of 2.64 to 2.69.
 
“With the new package, the engine runs in its sweet spot at any given speed, never straying from [there]... at any point from zero through top speed,” Saxman says. “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.”
 
Fleets whose trucks spend most of their time cruising at highway speeds will see the greatest improvements. The company claims there's no sacrifice in drivability during steep mountain climbs or stop-and-go traffic.