Aerodynamic trailer and truck design improvements that could save 1-billion gallons of diesel a year if implemented across the trucking industry were unveiled last month in Washington, DC, by a joint government-private industry partnership.

The Truck Manufacturers Assn. (TMA) and four of its members — International Truck and Engine Corp., Freightliner LLC, Mack Trucks Inc. and Volvo Trucks North America — spearheaded the effort, with funding and research support from the Dept. of Energy.

Each truck maker focused on a specific area of aerodynamic research and then agreed to pool its findings so all the manufacturers could gain from it, said Robert Clarke, TMA's president.

The combined effect of the aerodynamic improvements — such as trailer side skirts and boattails to reduce drag, sleeker tractor mirror packages, and reducing the gap between tractor and trailer — could cut tractor-trailer drag by up to 23%. That in turn would lead to a 10% improvement in fuel economy, Clarke said.

“If every tractor-trailer … in the U.S. adopted these improvements and gained 10% in fuel efficiency, it would translate into nearly 1-billion gallons per year of fuel savings,” Clarke said. For every 2% reduction in aerodynamic drag, there is a 1% improvement in fuel efficiency, he added.

All of these improvements are “practical and functional,” Mark Kachmarsky, chief project manager for Mack, told Fleet Owner. “We couldn't use complex solutions to reduce drag because being user-friendly was a key mandate of this project,” he explained. “Whatever we designed couldn't be an impediment to the operator's activity.”

For instance, Mack designed a retractable cab side fairing that would eliminate the gap between tractor and trailer at highway speed, but would also retract automatically at low speed so the fairing would not restrict vehicle maneuverability.

“This effort took a systems approach to fuel economy,” Patrick Charbonneau, vp-government relations for International, told Fleet Owner. “We all looked at how to make the overall tractor and trailer package work together better. These are also very practical design improvements we can implement in the near term. And as we [International, Freightliner, Mack and Volvo] collectively represent more than 75% of the Class 8 truck market, that means we can get these improvements to the industry faster.”