Truck OEMs that offer only diesel engines using selective catalytic reduction (SCR) after-treatment systems to meet EPA 2010 emission regulations have reacted strongly to the recent lawsuit filed by truck and engine maker Navistar against the U.S Environmental Protection Agency (EPA).

That suit, filed July 5 in the U.S. District Court for the District of Columbia, alleges that under certain conditions - considered by Navistar feasible to occur in real-world truck operation - those SCR systems fail to control emissions levels to the degree for which they were designed to certify engines as emissions-compliant under the 2010 federal rules.

In the suit, Navistar states the result is that “... EPA unlawfully and preferentially helped (and intends to continue to help) SCR engine manufacturers by making it easier for them to compete with other emission control technologies by reducing or eliminating the need for drivers to refill with DEF, which in turn allows SCR engines to become heavy polluters above the lawful emission standards.”

Not so fast, say competitors that responded to Fleet Owner queries seeking their reactions to the lawsuit.

“Given the history, we’re not surprised by this - it sounds like more of the same,” said John Walsh, Mack Trucks director of media relations. “The irony is that, a year and a half after the regulations went into effect, they [Navistar] still can’t meet the standard without credits, and their trucks are still spewing two-and-a-half times the pollutants allowed.

“We [Mack] think their complaint has no merit,” Walsh added. “We intend to file a motion to intervene.”

Brandon Borgna, manager of media relations for Volvo Trucks North America, essentially concurred. “We intend to file a motion to intervene,” he stated. “We think the [Navistar] complaint is frivolous, and that it won’t go anywhere.

“The market has already decided that SCR-equipped engines are the preferred choice in terms of performance and fuel economy, as well as the environment,” Borgna continued. “And EPA has said they believe the technology is highly effective.”