The decision contrasts with Cummins and Paccar plans to keep offering 2026 engines as EPA draft revisions ease compliance penalties and warranty requirements. DTNA plans Gen 6 DD13 and DD15 engine availability in January 2027 and DD16 production in January 2028 under the new emissions standards. EPA’s draft revision of its nitrogen oxide emissions rule includes rolling back warranty requirements for new heavy-duty trucks alongside the softer compliance standards. (American Trucking Associations)However, EPA is set to leave in place a Biden-era requirement that NOx emissions for heavy-duty trucks fall to 35 milligrams per horsepower-hour from 200 mg/hp-hr, as expected. DTNA launched its EPA 2027-compliant engines in February, with the Detroit Gen 6 portfolio comprising 13-liter DD13, 15-liter DD15 and 16-liter DD16 engines for heavy-duty Freightliner and Western Star trucks.