TORONTO, — Truck makers are facing face hard questions heading toward the next emissions bar set by the U.S. Environmental Protection Agency (EPA). Starting in 2007 and phasing in through 2010, particulates and nitrous oxides will need to be reduced by 90 percent-even over the tough targets most heavy diesels must meet now.

Already, truck owners are looking for hints about how to time purchases of trucks equipped with new emission-reduction technology for post-2006. Earlier this year, they caught a glimpse of what lay ahead during a summit of North American diesel engine suppliers. The consensus? There is none. Manufacturers are split on which next-generation emission technology is best.

Freightliner LLC and Volvo Trucks North America both champion selective catalytic reduction (SCR), which uses urea injection into the exhaust to remove NOx, leaving nitrogen and water. It’s no coincidence that those with strong ties to Europe favour SCR, the preferred technology to reach European emission regulations set to hit between now and 2008. The summit left little doubt that SCR is the more proven option: in use today on transit buses in Europe, by 2007 more than one million SCR-powered vehicles a year will be in production, significantly lowering their unit costs and establishing a lengthy track record for reliability and performance.

The EPA, however, endorses other technologies involving NOx adsorbers, which product planners at Cummins, Caterpillar, and International also say are a more promising alternative to SCR. SCR detractors raise doubts that fuel stops in North America will be equipped to supply urea by 2007. The EPA frets that you can run an SCR engine with the urea tank dry, thus defeating the emission benefits.

Trucking company executives speaking at the conference said they don’t much care which path manufacturers take. They worry about having enough time to gauge the reliability and performance of the engines themselves. Kevin Knight, chairman of Knight Transportation, with 2,100 power units, said his company won’t commit to any new iron until after extensive on-road tests. Glenn Brown, chairman of Contract Freighters (CFI), bluntly stated that his 2,400-truck fleet would time its purchases to avoid engines made from 2007 to 2009.

One thing seems certain: no one wants a boom-bust sales cycle in 2006 and 2007 similar to the pre-buy phenomenon leading up to tougher standards that took effect in October 2002.

“As a company, we say to customers, ‘Buy our truck because the operating costs over the life of the vehicle, plus the higher residual value, make it a good investment,'” says Kenworth general manager Bob Christensen. “That’s a challenge when your customer is unsure about costs related to engines and about residual values because of new emission technology. We need to start focusing on lifecycle costs now with an eye toward 2007, and on giving everyone ample time to get comfortable with whatever technologies engine companies use to meet the EPA targets.”

No one can afford a crisis of confidence again, he says. Not fleets, and certainly not their suppliers.