PORTLAND, Ore. - When Freightliner introduced its new Cascadia Class 8 tractor in May, it said it was confident the new truck boasted best-in-class aerodynamics. Now, the company says it has the proof...
PORTLAND, Ore. – When Freightliner introduced its new Cascadia Class 8 tractor in May, it said it was confident the new truck boasted best-in-class aerodynamics. Now, the company says it has the proof.
Freightliner officials say independent testing by the Auto Research Center has proven the Cascadia is more aerodynamic than the International ProStar, Kenworth T660, Peterbilt 386 and Volvo 780. Testing was conducted at Freightliner’s own wind tunnel in Portland, a wind tunnel built exclusively for the testing of Class 8 vehicles.
Researchers measured wind drag on the front, sides and back of the tractor as well as the front of a trailer, the company reports. Freightliner officials say the ProStar experienced 7.8% more drag, the 780 showed 9.6% more drag, the T660 showed 18.8% more drag and the Pete 386 reportedly experienced 22.9% more drag than the Cascadia.
“My overall conclusion from this test is that based upon the results, the Freightliner Cascadia is the most aerodynamic of the five tractors tested,” said Mike Camosy, ARC operations manager, in a written report.
Freightliner’s Michael Delaney, senior vice-president of marketing, added: “We read our competitors’ claims on aerodynamics and wonder if they were based on comparisons with older models or against models with very different spec’s. It didn’t appear to be scientifically based. Aerodynamic efficiency isn’t a function of looks – it’s about measured air flow resistance. We were confident the Cascadia would prove to be superior in this area when solid science was applied. The results proved what we expected,” Delaney said.
Freightliner officials say the Cascadia can save customers between US$950 and $2,750 per truck each year, assuming trucks are driven 144,000 miles a year with fuel at US$3 per gallon and driving at 60 mph.
“The Cascadia had already accumulated 2,500 hours of aerodynamic testing over 16 months through our engineering group so we were pretty confident going in,” said Delaney. “The Cascadia is fuel efficient, quiet, comfortable and a kick to drive. It really is a smart choice for better business and lifestyle.”
However, just days later, Inernational Truck and Engine publicly challenged Freightliner’s findings, based largely on the fact a full-sized trailer was not included in wind tunnel testing.
“No truck that we have tested has outperformed our new ProStar in testing to Society of Automotive Engineers (SAE) standards, which include the whole trailer as well as the tractor in real-word simulations. Freightliner simply cannot say that,” said Steve Gilligan, assistant general manager of International’s Heavy Vehicle Center.
“Since their test does not include the aft section of the trailer, it does not allow a wake to form behind the vehicle as it does on the road,” added Bob Weber, International’s chief engineer of heavy vehicles.
He added the end of the trailer should be included in testing because it has “a profound influence on the overall aerodynamic drag of the tractor-trailer combination.”
International engineers say the ProStar was developed specifically to minimize the wake that forms at the aft of the trailer, delivering excellent airflow even when driven through crosswinds.
“It does not appear that Freightliner is presenting aerodynamic drag data based on the wind-averaged drag coefficient formulation recommended in the SAE best practice for truck and bus wind-tunnel testing (SAE J1252),” Weber said.
International plans to delve into the issue further, and has placed an order for a Cascadia for testing purposes.
In the past, International conducted full-scale tractor-trailer testing at Canada’s National Research Council Institute for Aerospace Research in Ottawa, Ont.
When tested there, the ProStar proved to deliver best-in-class aerodynamics, the company said.
International officials vow to support independent third-party fuel economy testing of the Cascadia compared to the ProStar and the company promises to publish the results when they become available.
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