Aerodynamics appears to be the next frontier in terms of heavy-duty truck fuel efficiency. And that outlook is promising, if the experiences of Interstate Distributor is any indication. The Tacoma, WA., fleet, which operates more than 2,000 tractors and 6,800 trailers, is currently installing aerodynamic side skirts on 2,058 of its trailers. The skid skirts are manufactured by Seattle based Aeroflex. The fleet is getting the cost of installation partially offset via a $175,000 grant from the Pacific Northwest Pollution Prevention Resource Center (PPRC). PPRC received funding from a $875,972 grant from the Environmental Protection Agency’s (EPA) Diesel Emissions Reduction Act (DERA) which it is distributing to public and private fleets in the nationwide to boost the adoption of fuel-saving technologies such as trailer skirts.

In a discussion with trucking journalists, Lee Owens, Interstate’s senior vice president of maintenance and facilities, said Interstate Distributor has tested trailer side skirts for the past few years, achieving a “conservative” 3 to 5 percent improvement in fuel economy, depending on route, speed and road conditions. “With that kind of efficiency gain, we’d have installed side fairings on our trailers whether they were mandated or not,” Owen added. “The benefits are too big to ignore.”

Owens believes that without the EPA grant, Interstate could expect to recoup its trailer skirt investment in approximately 2 years. But thanks to the EPA grant, the ROI time is now cut by a third. The California Air Resource Board (CARB) estimates the average cost of trailer compliance with its new mandate for box-type trailers 53-feet or longer to be around $2,900 per unit. Additionally, CARB estimates that if fleets achieve gains of 7 to 10 percent in fuel economy by using aerodynamic panels and skirts, they will save $4,000 to $5,700 per year per tractor-trailer combination in fuel costs.

According to PPRC, Interstate’s trailer aerodynamics project is expected to save 1.1 million gallons of diesel a year, over 16 million gallons over the lifespan of the skirts, while preventing the emission of 182,633 tons of greenhouse gases. Owens says those fuel savings will more than help offset the costs associated with installing the trailer side skirts.