This could save 3.4 billions gallons of diesel fuel a year. The devices are being wind-tunnel tested now.
Pressure differences around the vehicles cause aerodynamic drag, and traveling at highway speeds, a big rig uses more than half the energy produced by its engine to overcome the drag. Rolling resistance consumes about 30 percent of usable energy.
Fitting devices into spots that produce the most severe drag — the trailer base, the underbody and area between the tractor and trailer — could increase fuel efficiency as much as 12 percent, researchers say.