Daimler Trucks North America and Volvo Trucks North America July 22 issued sharp rebukes of a “fluid economy” road test commissioned by Navistar International Corp. The test compares the performance of trucks equipped with selective catalytic reduction to trucks equipped with exhaust gas reduction technology. Both technologies reduce emissions of nitrous oxide.
Earlier, Navistar announced it was challenging claims by its competitors that diesel trucks equipped with SCR were achieving notably improved fuel economy. Instead, Navistar proposed “fluid economy,” tracking consumption of both DEF and diesel fuel, as a better measuring stick for diesel engine efficiency and performance.
In a statement, DTNA’s Freightliner said, “The credibility or validity of the test published by Navistar cannot be judged without revelation of more details. We run stringent fuel economy tests which are both accurate and substantiated. 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.”
The company added that the 440-mile test run by Navistar is too short for testing modern EPA 2010-compliant trucks in a working environment.
Meanwhile, Volvo Group strongly defended the effectiveness of SCR and warned against revamping the regulations with the roll-out of EPA 2010-compliant engines already well under way. “We question the need to make modifications to SCR strategies just six months after SCR products were brought to market,” said Steve Berry, director of government relations with Volvo Powertrain.
Navistar is the only U.S. heavy-duty truck manufacturer to use only an EGR solution to meet stringent 2010 U.S. Environmental Protection Agency regulations limiting diesel pollutants. All other North American engine manufacturers have elected to use SCR technology, which sprays hot diesel exhaust gas with a urea-based diesel exhaust fluid.