Thirteen miles per gallon was the high water mark the last time the SuperTruck program brought cutting-edge demonstration trucks to America’s highways in 2016. This year, International’s SuperTruck 2 reached even further, hitting 16 MPG in flatland duty cycles across Illinois with a 65,000-lb. gross vehicle weight, according to Dean Oppermann, chief engineer of advanced truck at Navistar.
There’s no magic bullet technology that made this level of trucking fuel efficiency possible. It’s a collection of design refinements, equipment enhancements, and product innovation that made it possible. One of the standouts is the International SuperTruck’s hybrid powertrain. Oppermann explained that the SuperTruck 2 program’s primary focus was on brake thermal efficiency in the engine, as well as improvements on the vehicle side. Navistar engineers merged a hybrid system featuring an electric motor outputting around 150 kilowatts, backed by a 30-kilowatt battery, with International’s S13 13-liter engine.
In practical terms, the electric motor can power the powertrain and start the engine, effectively facilitating power transfer in both directions. The setup allows the electric power to be utilized more efficiently at stops, enabling higher torque for better launches. As the vehicle reaches a specific speed or load, the system switches from electric to diesel operation.
The tractor is connected to a trailer, custom-built by Navistar, featuring lightweight composite materials and aerodynamic optimizations such as a curved front and shaped top corners, which are difficult to achieve with traditional construction methods.
“I was the chief engineer for our first SuperTruck, and during development, what we found was the aerodynamics of the vehicle were limited by the trailer or defined by the trailer,” Oppermann noted. “I used to tell everyone that we designed the first SuperTruck from the back forward because it isn’t until you clean up the trailer that you can optimize the tractor. The trailer causes a lot of the drag.”
Watch the video above for a look, both inside and out, at the International SuperTruck 2 and how it achieved 16 MPG.
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