Aerodynamic tractors have been a growing part of the heavy-duty truck market for decades. With much of the tractor aero gains already carved out from years of wind-tunnel testing and refined engineering, attention now has swung to trailers. MinStar, a long-haul dry van fleet running out of Eagan, Minn., began experimenting with aerodynamic tractors when fuel was still less than $1 a gallon. It wasn’t until last year that MinStar began working with trailer aerodynamic
“We had some classic models in our fleet a few years ago,” says Mitch Miller, MinStar president. “But we stay away from them now entirely because of the cost of fuel.”
The carrier’s primary focus now is on closing the gap between the cab and the trailer with adjustable fifth wheels and cab extenders, while also using tank fairings and trailer skirts.
“Based on our own testing, a full aerodynamic tractor-trailer combination gets ¾ of a mile per gallon better fuel economy than a nonaerodynamic rig,” Miller says. “We feel that aerodynamics allow us to operate a fuel-efficient vehicle for $800 a month less than for a nonaerodynamic model.”
“When diesel fuel prices drop to less than $3 a gallon, there is not much interest in paying for an aerodynamic improvement that will take six years to pay for itself,” says Dave McKenna, director of powertrain sales and marketing at Mack Trucks. “But at approximately $4 per gallon, there are a lot of ‘aero-religious’ converts.”
The other driving force for more aerodynamic tractor-trailers is environmental concern for lower emissions. That’s why California and the U.S. Environmental Protection Agency have been pushing aero equipment aggressively.
“Already many millions of dollars have been earmarked by the U.S. Department of Energy to help the cause,” says Sean Graham, president of Freight Wing, an aerodynamic trailer component designer and manufacturer involved in DOE’s effort. “Our goal is to realize a 15 percent improvement in fuel economy over trailers without fairings.”
