Roof fairings will improve fuel efficiency, and the more aerodynamically shaped the roof air fairing, the better the fuel economy.
For 53' dry vans and refrigerated trailers, full height roof fairings create a smooth transition from the windshield to the full height of the trailer. These fairings may simply be the top of a full-height sleeper cab or an additional part above a low, mid, or high cab.
For day cabs, a roof fairing is often an additional part that can be mounted to the low-roof cab. In some cases, an adjustable roof fairing can be installed and lowered to limit drag when the tractor is not pulling a trailer.
For tanker or flat bed trailers, tractors and their cab height should be specified to match the trailer as best as possible. Using a full-height cab that generally matches a 53’ van trailer will create higher drag than needed and thereby increase fuel expense up to 10%.
Due to lower drag
Full-height roof air fairing decreases fuel economy in bobtail, or in trucks hauling flat or tanker trailers
“We continue to update our fleet with more fuel efficient post-2014 U.S. Environmental Protection Agency emission compliant engines, install aerodynamic devices on our tractors, and equip our trailers with trailer blades, which all lead to meaningful improvement in fuel efficiency.” — Knight Transportation
“Appearance and detail of our equipment means a lot to our drivers. Drive wheel fairings don’t just save us money, but our drivers like them too.” — Brad Pinchuk, Hirschbach
“Sleeper tractor aerodynamics have been finely tuned by all OEMs. Eliminating various features can add 10% to a fleet’s fuel expense,” — Chief engineer at a major truck builder.
The Confidence Matrix has been issued to help fleets make decisions about tractor aerodynamic devices.