Cummins to delay launch of 2027 X15 diesel engine

7 August 2025

Cummins will delay the launch of its EPA 2027 compliant X15 heavy-duty diesel engine until late 2026, citing ongoing uncertainty around the US federal emission regulations, Transport Topics reported.

Cummins unveiled the next generation X15 engine in February, and said the engine will comply with the US Environmental Protection Agency (EPA) and California Air Resources Board (CARB) 2027 emission regulations.

The engine utilizes a belt-driven, high output 48-volt alternator and electric heating of the aftertreatment system to meet the 2027 emission standards. Cummins said the new X15 engine would be available for pre-order in mid-2025 and deliveries would begin in 2026.

However, in March the EPA started a major review of air emission regulations, including the Phase 3 GHG emission standards as well as the 2027 NOx emission standards for heavy-duty engines and vehicles. As a result, Cummins is delaying the 2027 X15 diesel engine launch, CEO Jennifer Rumsey told investors during the company’s second-quarter 2025 earnings call.

A pre-buy of heavy-duty trucks was anticipated before the stricter emission standards were to take effect but with the uncertainty, fleets have kept their pocketbooks closed. In Q2 2025, Cummins’ heavy-duty engine sales in North America decreased 29% year over year to 22,000 units, and executives expect the third quarter to be much worse. Nonetheless, Cummins still believes that there will be a more stringent 2027 NOx regulation, and there may be a belated pre-buy as a result.

Source: Transport Topics