Trailer add-on could cut up to 3 gallons of diesel per 1,000 miles

Behind a trailer's wheels, the air tumbles. A loaded tractor-trailer at highway speed pushes a large, boxy shape through the air, and most aerodynamic work in the industry has gone to the front and sides of that box. FlowBelow Aero, a Texas company that builds aerodynamic parts for Class 8 heavy trucks and their trailers, is working on the part of the rig that gets less attention. Its AeroSlider, shown at the American Trucking Associations' Management Conference & Exhibition in Charlotte, North Carolina, from October 17 to 20, is a fairing system aimed at the wheels, suspension and underbody around the trailer's tandem axles. The company says it can save up to three gallons of diesel for every 1,000 miles.

The principle is redirection rather than blocking. As air passes the wheels, the fairings guide it outward and backward, which reduces the turbulence around the suspension and in the wake behind the trailer, and lowers drag. That effect is particularly strong at speeds above 31 miles per hour (50 kilometres per hour). The part also moves with the trailer's sliding suspension. Fleets shift axles to spread cargo weight and to stay within road weight limits, and the AeroSlider travels with them, so its fairings stay in position without readjustment.

The fuel figures come from tests. The redesign was developed with computational fluid dynamics (computer simulation of airflow), wind-tunnel experiments and track testing. In June 2026, the independent firm MVT Solutions ran it on 2019 International LT tractors pulling loaded 53-foot dry vans. With side skirts and wheel covers already fitted, the redesigned rear fairings and flow-through mud flaps cut fuel use by 1.77 gallons per 1,000 miles. Separate testing found the wheel covers could save another 1.23 gallons over the same distance. The "up to three gallons" headline figure is the company's own.

For a fleet, the payoff is at the pump. The company's arithmetic starts from the national average diesel price of USD 6.179 per gallon on October 12, which turns three gallons saved per 1,000 miles into USD 18.54, or about USD 1,854 a year for a trailer covering 100,000 miles. FlowBelow's president and CTO, Josh Butler, said the goal was a payback of under 18 months at USD 3.00 diesel. At today's prices, he said, payback can be less than 12 months, even for trailers that travel only 30,000 miles a year. The system is designed to fit almost any dry van or refrigerated trailer, and it is a redesign of a product first unveiled in 2017.

Those numbers are the company's, and the fuel gains rest on a single independent test series run in June 2026 on one set of tractors and trailers. The savings also depend on how many miles a trailer covers and on the diesel price, both of which will move. Neither a sticker price nor the number of trucks already running with the AeroSlider has been put on the table, so the payback claim cannot yet be checked against a real fleet's books.