While truck and engine manufacturers are working to boost fuel economy and reduce emissions in the face of looming regulations, it’s a timely opportunity to recap aerodynamic devices and the benefits they offer fleets.

As part of Greenhouse Gas regulations (GHG14), trucks and buses model years 2014-18 are projected to reduce oil consumption by 530 million barrels and greenhouse gas emissions by 270 million metric tons. Although GHG14 does not include trailers or aerodynamic add-ons, EPA has discussed a later phase of GHG regulations, and the consensus is that trailer aero devices will be included, according to Rick Mihelic, manager of vehicle performance and engineering analysis for Peterbilt Motors Co.

“EPA and NHTSA rulemaking requires an advance period between being issued and taking effect, so it is likely at this point that the earliest additional new GHG rulemaking would be 2019 or later,” he says. “CARB rules for 2013 require the adoption of SmartWay-equipped trailers; these rules will likely increase the national adoption rate for trailer aero devices.”

According to Mihelic, the highly competitive freight marketplace encourages carriers to constantly improve efficiencies; state and federal regulations and guides also encourage adoption of aero devices. Peterbilt has demonstrated through the DOE SuperTruck program significant improvements in tractor/trailer fuel economy through a prototype total system design, including aerodynamic device-equipped trailers, he says.

Frank Bio, Volvo Trucks product manager—trucks, said his company will continue to recommend aerodynamic devices and other features that assist in improving fuel efficiency. “As part of ongoing work to further improve fuel efficiency, Volvo Trucks introduced in early 2011 advanced aerodynamic components for the Volvo VNL model highway trucks,” he says. New exterior components included redesigned mirror heads with aerodynamic shrouds and arms, redesigned hood mirrors, and additional ground effect features below the bumper and side fairings.

Trailer fairings alone can increase fuel efficiency by up to approximately 5%, according to manufacturers, but it’s important to consider the tractor when quoting trailer efficiency numbers. “The 5% improvements may be realized when there is a less aerodynamic tractor hauling the trailer, but the same may not be true when hauled by a more aerodynamic tractor,” Bio notes.

Mihelic says the net fuel economy gain is very dependent on multiple factors like tractor configuration, trailer gap, driving habits, use of vehicle speed limiters, etc. EPA SmartWay requires that a trailer skirt package alone add at least a 4% fuel economy improvement. In combination with other trailer devices such as boat tails, gap reducers and aerodynamic tractors, net MPG savings can be in the 10% to 15% range.

Because of fuel savings and the simple idea that embracing changes now will ease a fleet’s business into the future, many fleets already are using trailer fairings and other aero devices. But for those that haven’t taken the step yet, truck makers are there to help.

Consult vehicle OEMs for guidance on selecting and combining systems to get the best performance from a tractor/trailer combination. Review the research and testing done by industry and government agencies, and engage in industry meetings where aero devices are key topics. If possible, pilot aero devices in a controlled manner for your operations and quantify your own savings, suggests Mihelic.

Bio advises: match the tractor height to the trailer using a roof fairing or full height cab; shorten the trailer gap and add cab extenders; add chassis fairings and ground effect devices; and consider additional manufacturer-recommended devices.

“Since aerodynamic feature returns are not additive, the customer needs to work with the manufacturer for realistic numbers when adding a series of aero devices,” Bio said. “Start with a repeatable number from your fleet and make your own comparisons as devices are added at each purchase, but remember that each year brings new fuel saving devices that may not be related to aerodynamics.”