SACRAMENTO, Calif. – A handful of Navistar’s competitors fired back at their rival and questioned the EPA’s recent decision to reexamine the 2010 engine rule six months after SCR engines hit the market.

The comments were part of a public workshop won by Navistar for dropping its lawsuits against environmental regulators.

Navistar — the only engine maker not to choose SCR emissions-reduction technology for 2010 — is contesting what it says are “compliance loopholes” for SCR engines.

The company complains that EPA’s oversight allows SCR engines to exceed NOx emissions standards if drivers neglect to put diesel exhaust fluid (DEF) in their engines.

Navistar likens this to a giving some engine makers a “licence to pollute” and at the workshop showed a video of the same title.

But while representatives of Volvo, Mack and Cummins were at the workshop to defend their technology, some went on the offensive.

“We question the need to make modifications to SCR strategies just six months after SCR products were brought to market,” said Steve Berry, director, Government Relations for Volvo Powertrain. “These strategies were thoughtfully developed in good faith by EPA, CARB, and EMA, applying their collective best judgment to balance SCR operation with other critical issues, not the least of which is safety.”

Moreover, we find it very unsettling that the requirements … for this Workshop were agreed to in the context of litigation with a non-SCR manufacturer,” Berry continued. “We’re concerned about the precedent that’s being set by these proceedings, whereby the regulated provisions by which a technology is to be deemed acceptable for production are being driven by a competitor using alternative technology.”

Berry said that despite Navistar’s claims, there is no evidence of DEF refill or SCR tampering issues in the field and he believes “it is premature to impose new restrictions in the absence of any evidence of need.”

In fact, since warning alarms sound off when DEF is running low – and the engine will eventually derate if the DEF tank isn’t topped up — many SCR suppliers insist it’s highly unlikely drivers will neglect DEF and hardly lead to the environmental disaster Navistar claims would occur.

Navistar’s contention that drivers can “trick” the engine by substituting plain water for DEF (and, according to its video commentary, freely driven up to 11,000 miles with H2O) is also another example of misinformation, says John Walsh of Mack Trucks.

Were such a condition to occur, he says in an email to todaystrucking.com, sensors would be triggered. And in rare cases where the driver doesn’t replace the DEF, the engine would derate and ultimately be limited to 5 mph at the time of diesel fuel refill.

Walsh then fired back at Navistar, pointing out the company doesn’t have an engine that meets the 2010 0.2 g NOx standard and is allowed to sell medium-duty engines that exceed the limit by more than double thanks to EPA emissions credits it banked prior to Jan. 1 2010.

“We just find it so ironic that a manufacturer who so far this year has sold exclusively thousands of higher-emitting pre-EPA10 engines, and who has opted for an EPA10 approach that emits twice as much NOx as SCR and tons of additional greenhouse gases into the atmosphere (by burning more fuel), is now concerned about the environment?

“Is the use of credits to far exceed the .2 g NOx standard a ‘loophole’?

His Mack-Volvo counterpart, John Miles, was just as direct in his workshop testimony as he questioned environmental regulators’ decision to reconsider parts of the rule.

“And why?” he asked rhetorically. “In large part because of concerns being raised by a single competitor …

“A competitor that said it was ready for the new standards, yet lobbied for a delay in implementation, and when that failed, resorted to lawsuits against the regulators.

He also blasted Navistar for launching a campaign that assumes “that most of its customers, and the trucking industry as a whole, are hell-bent on illegal circumvention of emissions controls.”