CHICAGO, Ill. — Navistar has been undergoing various aerodynamic tests recently, including wind tunnel and over-the-road testing, which the company says confirms that its International ProStar is the most fuel-efficient Class 8 truck in the industry.

In the wind tunnel test, Navistar put its International ProStar and LoneStar up against Freightliner’s Cascadia and the Kenworth T660. The company said the results had the ProStar showing greater efficiency.

“It was 7.3% more aerodynamic than the Freightliner Cascadia, and 8.2% better than the Kenworth T660,” said Ron Schoon, the chief engineer of Navistar’s aerodynamics department, who noted that aerodynamic drag results in a two-to-one fuel consumption increase.

“Again with that two-to-one trade, that means ProStar’s aerodynamic advantage really is truly significant, yielding 3.5% to 4% contribution to a fuel economy advantage out on the highway. Even look at the LoneStar – its (test results are) as good as the Cascadia,” Schoon added.

The over-the-road test was equally as impressive, according to Navistar. The 444-mile circular route, over-the-road test pitted the ProStar against the Cascadia, each with similar specifications, Navistar officials said during a conference call with media. The results indicated the ProStar was the most fuel efficient, in a long-distance test, according to Navistar.

“ProStar is 7% more fuel efficient than the Cascadia,” said Bob Weber, the chief engineer for Navistar’s heavy-duty vehicle centre. “The 7% fuel efficiency can save a customer $5,800 per truck annually. That’s nearly $30,000 over a five-year ownership, compared to our closest competitor. This advantage is huge for our customer.”

The wind tunnel tests were conducted in March and April, at a nine-metre wind tunnel test facility located at the National Research Council in Ottawa. The over-the-road test was conducted by a third party endorser, Transportation Research Centre, which followed the TMC Type IV test procedures. The test was between two vehicles with almost identical specifications, and both pulling trailers, Navistar claimed.

Navistar’s TMC Type IV testing was in addition to a previous SAE Type III test the company conducted last fall which it said showed the ProStar to be 5.7% more efficient than the Cascadia.

Daimler Trucks North America, Freightliner’s parent company, has disputed previous aerodynamic claims by Navistar. It insists its own tests have shown the Cascadia to be more aerodynamic than its rival.