Putting a new cost-efficiency measure—“fluid economy”-- into play, Navistar Inc. announced yesterday that independent third-party testing has proved its International ProStar+ tractor powered by its MaxxForce 13 Advanced EGR diesel is more efficient than two truck/engine combinations it regards as competitive on-highway Class 8 truck models.

The OEM said the testing that it hired the independent Transportation Research Center Inc. (TRC.) to conduct showed its truck/engine combo is “the industry leader in fluid economy—a measurement of diesel fuel plus liquid urea consumed and the new standard of comparison for Class 8 trucks.” Specifically, Navistar said the tests results “show nearly a 1% to 2.5% advantage” using the new measure of fluid economy.

“With the ProStar+, we continue to have the most efficient Class 8 truck on the road,” said Jim Hebe, Navistar sr vp, North American sales operations, during a news webinar held yesterday afternoon for the media. “We weren’t satisfied with simply being the best—we were determined to make the best even better and the results speak for themselves.”

While fuel economy-- diesel MPG—has been a traditional measure of vehicle efficiency, according to Michael Cerilli, vp—North American truck marketing, today with different trucks offering different technologies to meet EPA 2010 emissions, fuel economy “doesn’t tell the whole story.” He pointed out that competitors’ trucks use an SCR solution that requires the use of liquid urea (aka DEF) “and, like diesel fuel, liquid urea costs money.”

Determined to back up its case for fluid economy to be seen as the new, more exact measure of efficiency, Navistar commissioned TRC to conduct a head-to-head fluid economy comparison. TRC performed independent TMC (Technology & Maintenance Council) Type IV testing of three EPA 2010-compliant trucks. An International ProStar+ with MaxxForce Advanced EGR engine was put up against a Freightliner Cascadia and a Kenworth T660, both powered by engines that require the use of DEF by their emissions aftertreatment systems, said Mike Baus, director of integrated testing and validation.

However, while the MaxxForce 13 engine was rated 430 hp and 1,550 lbs-ft of torque, the engines in the other trucks each boasted about two liters more of displacement: The Freightliner was powered by a Detroit Diesel DD15, rated 455 hp and 1,550 lbs-ft, and the Kenworth by a Cummins ISX15, rated 435 hp and 1,450 lbs-ft. In response to reporters’ questions on this seeming discrepancy in specs, Hebe said the competitors’ trucks were purchased from dealer stock at a time when only 15-liter engines were available. And both Hebe and Baus said the trucks were nonetheless spec’ed to maximize their fuel efficiency.

According to Baus, during the testing, only one tank of diesel per truck was allowed and each truck ran three 444-mile runs on public highways, in real-world conditions. Drivers and trailers were switched at the mid-point of each test.

“The [test] results were clear,” said Cerilli. “In the comparison of fluid economy, the International ProStar+ with MaxxForce Advanced EGR consistently outperformed the competing trucks 1% to 2.5%.The bottom line? It all adds up to ProStar+. In addition to better fluid economy, ProStar+ with MaxxForce Advanced EGR gives you the advantage of hassle-free 2010 emissions compliance.” In a related news release, Navistar also made the argument that “as vehicle weight continues to be a top priority for customers, the ProStar+ is 700 lbs lighter than its predecessor. When you include the MaxxForce 13, with its durable, lightweight compacted graphite iron (CGI) cylinder block, and MaxxForce Advanced EGR emissions technology, the ProStar+ has an additional 600-lb advantage versus the leading 15-liter engine, providing an extra 1,300 lbs of added payload capacity and fluid economy benefits. With ProStar+ with MaxxForce 13, a customer can still get the power they’ve come to expect from a 15-liter engine with considerably less weight .”

“If liquid urea SCR trucks can’t compete on fluid economy,” said Hebe, “then why would customers want to deal with the cost and hassle of adding and maintaining after-treatment equipment, finding and filling up with liquid urea and retraining technicians?

“When you add up all the advantages of ProStar+ and then consider the costs and hassles of the competitive emissions solution, the answer is clear: ProStar+ with MaxxForce Advanced EGR is the smart choice,” Hebe added.

Navistar has issued a white paper on the testing .