Cummins has been planning to debut a diesel-powered version of the engine in its X15 fuel agnostic platform in early 2026, yet with changes to environmental regulations this year, the company is pumping the brakes.
Overdrive’s sister fleet publication CCJ reported Thursday that with the difficulty truck and engine makers are facing in the shifting sands of emissions regulations, Cummins will delay the launch of its newest diesel until late 2026.
Cummins Chairman and CEO Jennifer Rumsey said she estimated the delay for the new diesel might be around six months, citing uncertainty around regulations and tariffs, too, "which created an environment where, even though it was a more efficient product that we thought could bring some value to customers, the demand was a concern."
[Related: Cummins readies new diesel engine for 2027]
With market uncertainty given trade tariffs, product regulation and caution about the prospects for freight abound, Rumsey added that she expects North America heavy- and medium-duty truck volumes to decline 25% to 30% from second quarter levels as truck orders recently reached multiyear lows, and OEMs initiated reduced work weeks through the next three months.
She noted that the company would continue working to add to its 15-liter HELM engine platform, which will eventually include the X15 diesel, X15 natural gas and X15H hydrogen combustion engine.
"We are no longer launching the X15 earlier in the year. So at the end of next year," she said, "we’ll be launching those new platforms to comply with the '27 regulation and continue to keep the team focused on that."
The nature of those 2027 regulations is still up in the air, though.
[Related: EPA set to unravel 'disastrous' federal trucking emissions regulations]
The U.S. Environmental Protection Agency late last month proposed a draft rule rolling back the Greenhouse Gas Phase 3 rule and other GHG regulations dating back to 2011 for heavy-duty trucks and engines. Additionally, Congress in May voted to revoke strict state-level emissions standards enacted by California's Air Resources Board (CARB) -- the Advanced Clean Trucks and Omnibus Low-NOx rules.
EPA Administrator Lee Zeldin said in March his office also intends to revisit portions of the Biden-era Clean Trucks Plan, which includes the 2022 Heavy-Duty NOx rule -- standards requiring new, more stringent emissions controls over a wider range of heavy-duty engine operating conditions, and over an extended period of time.
Cummins expects its next generation diesel X15 to feature improved greenhouse gas and fuel efficiency benefits while retaining the same ratings of the current X15 (up to 605 horsepower and 2,050 ft-lb of torque) and optimizing powertrain integration with Eaton Cummins and Cummins-Meritor.
