Tests monitored by an independent research team at Freightliner’s heavy-truck wind tunnel show the new Cascadia Class 8 tractor to have the lowest aerodynamic drag compared to four similarly spec’ed competitive models, according to the truck manufacturer.

Auto Research Center Inc., an Indianapolis-based aerodynamics research firm that has also worked with NASCAR, other racing teams and various vehicle manufacturers, ran the tests during the summer. They measured wind drag on the front, sides and back of five tractors, as well as the front of the trailer with a 48-in. tractor-trailer gap.

Overall, Freightliner reported that its Cascadia exhibited 7.8% less aerodynamic drag than the International ProStar, 9.6% less than the Volvo 780, 18.8% less than the Kenworth T660 and 22.9% less than the Peterbilt 386.

“My overall conclusion from this test is that based upon the results, the Freightliner Cascadia is the most aerodynamic of the five tractors tested,” according to a written report by Mike Camosy, ARC operations manager.

Roy Wiley, a spokesperson for International, told Fleet Owner that the company had not seen the full results from the tests, but he pointed out that the Freightliner wind tunnel only accommodates a Class 8 tractor and the first few feet of a trailer. “Trailers are pretty big and they influence drag and fuel economy greatly,” Wiley said. “We do our testing in a Canadian wind tunnel that accommodates the entire tractor and trailer so we can look at all wind directions, including tail winds.”

Responding by email to a request for comment from Fleet Owner, a spokesperson for Volvo Trucks of North America said that the company “prefers not to comment regarding other companies' performance claims. However, there can be no dispute that Volvo's proven aerodynamic advanced trucks, plus its constant focus on improvements to vehicle and driver efficiency, enables its customers to achieve real fuel economy and productivity that drive success to their operation.”

Both Peterbilt and Kenworth also declined to comment on the wind tunnel test results.