EDITORIAL: Response to more-rigid NOx and GHG regs

In the waning days of 2022, the U.S. EPA delivered news that likely dimmed the good cheer of the season for many manufacturers in the heavy-duty (HD) truck industry. Not that it was unexpected, but the agency's final rule on HD diesel engine NOx emissions is stringent - more than 80% stricter than current standards and covering a wider range of engine operating conditions. The new limits begin with model year 2027 HD trucks.

The “two-phased approach” first increases stringency in NOx emissions from 0.2 to 0.035 g/bhp-hr by 2027 and again from 0.035 to 0.02 g/bhp-hr in MY 2031 - a 90% reduction in total. The new rule also increases useful life of governed vehicles by 1.5 to 2.5 times and extends emissions-related warranty requirements by 2.8 to 4.5 times, the EPA says.