WARRENVILLE, Ill. –You may want to add the term “fluid economy” to your truck vocabulary. It’s a term you’ll likely hear frequently from Navistar International as the company continues to forge its own path towards EPA2010 emissions compliance while avoiding selective catalytic reduction (SCR) exhaust aftertreatment.

When measuring the costs of operating EPA2010-compliant trucks and engines, Navistar officials are urging customers to consider the overall consumption of both diesel and diesel exhaust fluid (DEF), a key ingredient required by engines using SCR. Doing so makes its Advanced EGR solution look much more attractive, according to independent third-party test results recently released by Navistar.

The results show that when taking the consumption of DEF into account, the truck maker’s rivals using SCR actually consume more total fluid than the International ProStar+ with MaxxForce 13 engine.

The tests, conducted on public highways by the respected Transportation Research Center following the TMC Type IV protocol, found the International ProStar+ with MaxxForce 13 consumed nearly 1% less fluid (diesel and DEF) than the Freightliner Cascadia with Detroit Diesel DD15 and nearly 2.5% less fluid than the Kenworth T660 with 15-litre Cummins ISX.

When asked why the company compared its own 13-litre engine to its competitors’ 15-litre offerings, Navistar’s senior vice-president of North American sales operations Jim Hebe said they chose the most fuel-efficient spec’ offered by their rivals.

“They are the engines they told us were the most fuel efficient they had in their lineup,” Hebe said. “That’s what they’re telling their customers as well.”

Navistar officials also said 13-litre offerings weren’t yet available from Cummins or Detroit Diesel for testing.

When looking at diesel consumption alone, Navistar says its truck and engine combo was within about 1% of its competitors. The results, Hebe said, exceeded the company’s own expectations. Hebe said the company internally had decided it could make a strong case for its Advanced EGR solution if it could get to within 2% of the fuel economy achieved by its SCR rivals.

“The closer we got, the closer we came to realizing not only could we provide parity, we could beat their claims as well,” Hebe said.

Navistar, of course, is the only Class 8 truck manufacturer in North America to tackle EPA2010 emissions standards without exhaust aftertreatment. Instead, International trucks will use increased levels of exhaust gas recirculation (EGR) combined with an enhanced fuel system and electronics to meet EPA2010 requirements. All other manufacturers, meanwhile, will use SCR, which requires the addition of diesel exhaust fluid yet allows the engine to operate more efficiently because NOx is not limited in-cylinder. At times, the debate over which solution works best has turned hostile.

“We’ve sat back the last couple of years and we’ve been shot at from about every direction you could be shot at with regards to our strategy for meeting 2010 emissions,” Hebe said. “We’ve seen competitors walk in and show presentations to our customers that say they’re 9% better (in terms of fuel economy) than we are. That clearly wasn’t based on fact. One of the biggest disservices we’ve seen some competitors do to the industry, is they only talk about the one fluid, they only talk about fuel and forget there’s this thing required in their system called diesel exhaust fluid or urea.”

Indeed, fuel economy has become one of the strongest selling points for engine manufacturers using SCR. Generally, they claim a 3-5% improvement over EPA07 equivalent offerings.

Navistar, it should be noted, has been redeeming emissions credits as it continues to wind its way down to the EPA2010 limit of 0.2 grams/brake hp-hr of NOx. Yet the company says it will not require liquid urea-based SCR at any time and reiterated it has a 15-litre MaxxForce on schedule to be launched in early 2011.

The TMC Type IV testing protocol requires similarly-spec’d trucks to be operated over the same route. In this case, a 444-mile route in Indiana was chosen. Drivers and trailers were swapped at the midway point and the consumption of both fuel and DEF was measured carefully using the meter reading of a commercial diesel pump. Navistar officials also said their ProStar+ with MaxxForce 13 is as much as 1,300 lbs lighter than competitive offerings with 15-litre engines using SCR.

Hebe said the test results were made sweeter by the fact the tests were conducted over long-haul, on-highway duty cycles, where SCR is said to be at its greatest advantage.

“The sweet spot for SCR was long-haul, on-highway and we beat them there,” he said.

Navistar officials said further tests will be conducted, including direct comparisons to competitive 13-litre engines which it has now obtained.

Not surprisingly, Freightliner and Detroit Diesel parent company Daimler Trucks North America (DTNA) was quick to dispute the findings. The company has never backed down from a PR battle with its biggest rival.

Specifically, DTNA had a problem with how Navistar pitted its own 13-litre engine against a 15-litre Detroit Diesel.

“We run stringent fuel economy tests at DTNA which are both accurate and substantiated,” the company said in a statement. “We test back-to-back componentry which is comparable from both a truck and an engine perspective. Ratings, displacements, truck configuration and more are matched to achieve valid results. The combination chosen by our competitor does not comply with these basic premises for proper engineering work and thus doesn’t provide a trustworthy result.”

Daimler also contended the 440-mile test run was not long enough to adequately reflect diesel particulate filter (DPF) regeneration cycles. The company said it looks forward to conducting its own test once the International MaxxForce fully complies with the EPA2010 NOx limits.

“We’re eagerly anticipating acquiring an EPA2010-certified series production 12.4L MaxxForce engine in order to run our own comparison study,” the company said. “It is neither appropriate nor credible to compare the 12.4L MaxxForce ‘mystery’ engine with proven technology available in the market.”

As a parting shot, Daimler noted it had received more than 25,000 orders for EPA2010-compliant trucks and added “We are unaware of any announcements made by Navistar on their sales track record in this category to date.”

Such announcements from Navistar may not be forthcoming either. During the media conference call, Hebe said after securing supply deals with mega-fleets J.B. Hunt, Heartland Express and Boyd Bros., that it would no longer be publicly announcing every deal it lands.

“We have captured several other medium, small and very large fleets, many of whom are using our product and our engine for the first time,” Hebe said. “Suffice to say, interest around our product and where we’re going with the ProStar+ and MaxxForce 13 is really gaining ground. Most of these fleet operators want us to be a success, they want a no-hassle solution to 2010 and they’re not really sold on some of the things they’re seeing out there with regards to SCR and DEF. They want us to be able to deliver on our promises.”

With contradicting messages about fuel efficiency superiority, Truck News turned to the entirely uninvolved and unbiased FPInnovations for reaction. FPInnovations is a team or researchers that conducts the twice-annual Energotest to test the fuel-saving claims of equipment on behalf of its member fleets.

Researcher Marius-Dorin Surcel pointed out that fuel economy testing is tricky business.

“My opinion is that there are some aspects that should be considered when interpreting the results,” Surcel said. “Indeed, engines sizes were different: 13 L (Navistar) with 15 L engines (competitors); the results were 1% in fuel economy and 1-2.5% in ‘overall fluid economy.’ However, both are in or very close to the margin of error for a Type IV TM
C RP 1109 Test, which is an in-service test, which means on the road, in this case 700-km length route and the consumed fuel is measured using the fill-up method” (rather than weighing the fuel, as FPInnovations does).

Surcel speculated that the 1,300-lb weight savings offered by the International package might have helped its cause.

“Vehicle dynamic equations would (allow) for this type of vehicle near to a 1% fuel savings only from the weight difference,” noted Surcel.

For its part, Kenworth declined to comment on the test results.

To view the test results, visit www.internationaltrucks.com/results.