After months of speculation, Caterpillar has made it official: it will not have a heavy-duty, on-highway diesel engine for the U.S. market in 2010. Its current medium-duty truck diesels are also in question, although the company says it will partner with Navistar to develop new engines for that on-highway segment. Following that announcement in June, Cummins, the one independent truck engine maker remaining in North America, quickly announced supply agreements with each of the truck manufacturers.

And so the division between selective catalytic reduction (SCR) and high exhaust gas recirculation (EGR) becomes a bit muddier as we approach the 2010 deadline. All but one of the OEMs have chosen to build proprietary heavy-duty engines with the SCR technology; however, under the new Cummins agreements, Daimler, Paccar and Volvo will also offer a non-SCR Cummins ISX 15-liter option. Navistar continues to support the EGR-only approach for its own engines and will offer the Cummins as its one 15-liter engine option. Only Mack will go to market with just the SCR technology for its heavy-duty trucks.

Individually, the OEMs report significant progress with both approaches to meeting the 2010 requirements. As the following manufacturer-by-manufacturer reports indicate, field and fleet tests indicate excellent performance for the new engines.