Cummins to roll out MY-2027 engines in stages due to EPA NOx rule

Cummins will begin limited production of its model year 2027 X15 and X10 engines in January 2027, phasing them in gradually to meet stricter EPA nitrogen oxide (NOx) emissions standards. The Columbus, Indiana-based engine maker will continue producing current-generation X15, X12, and L9 engines during the transition, ensuring customers aren’t left stranded as the new rules take effect. The EPA’s draft rule, unveiled July 9, 2026, slashes NOx emissions for heavy-duty trucks from 200 mg/hp-hr to just 35 mg/hp-hr—an 82.5% reduction—but leaves manufacturers some flexibility on implementation timelines and compliance credits. Cummins CEO Jennifer Rumsey emphasized that the phased rollout is designed to maintain quality and build customer confidence through real-world operation rather than altering the company’s long-term strategy. “This is about improving the transition, not changing the destination,” she said. The EPA also shortened warranty requirements for emissions mitigation equipment from 450,000 miles or 10 years to 100,000 miles or five years, a change expected to reduce the price increase for MY-2027 trucks by up to $10,000. The X15 engine, which powers many of North America’s largest trucks and tractors, will see a redesigned selective catalytic reduction (SCR) system and a dedicated 48-volt alternator feeding two heaters—one before the diesel oxidation catalyst/diesel particulate filter and another before the SCR segment. Limited production of the MY-2027 X15 starts in January 2027, with full-scale output ramping up by the fourth quarter of that year. The X10, which replaces the L9 and X12 in Cummins’ lineup, will also enter limited production in January, reaching full production by the third quarter of 2027, subject to OEM launch plans. Cummins’ current X12 and L9 engines will remain available during the transition, though the company warns that further adjustments may be necessary if the final EPA rule differs materially from the July 9 draft. The EPA 2027-compliant X15 made its public debut at the Technology & Maintenance Council’s annual meeting in late March 2026, a year after Cummins delayed its initial launch due to regulatory uncertainty. Meanwhile, Daimler Truck North America (DTNA) has confirmed it will offer six EPA 2027-compliant engines across its Freightliner and Western Star lineups, with the X15 already selected as standard equipment for Kenworth’s C580 heavy-haul tractor. Cummins is betting big on the X10, which launched in March 2025, to drive growth in the heavy-duty truck engine market. Brett Merritt, president of Cummins’ engine business, told analysts in May 2026 that the X10 opens up new market opportunities, with Mack Trucks already integrating it into its Class 8 Granite vocational truck in six power profiles. The EPA’s NOx rule has cast a shadow over second-half 2026 truck sales, with Volvo Group CEO Martin Lundstedt warning on July 17 that the regulatory uncertainty could dampen orders. Cummins’ staggered introduction of MY-2027 engines reflects the broader industry’s cautious approach to compliance, balancing regulatory demands with operational stability.