Natural gas and battery-electric trucks gain ground as federal ZEV push stalls

Federal zero-emission vehicle incentives expired and California's clean-truck rules were nullified in 2025, but natural gas and battery-electric trucks still posted measurable adoption gains as fleets chased operating-cost wins over policy compliance.

How much are fleets saving with the Cummins X15N natural gas engine?

The Cummins X15N 15-liter natural gas engine completed its first full commercial year with 71% of fleets reporting lower costs versus diesel and 59% reporting savings versus other natural gas vehicles. The engine delivers diesel-like performance — a critical threshold for linehaul and regional fleets that previously avoided natural gas due to power and torque gaps.

Natural gas adoption historically stalled when fuel-price spreads narrowed or when fleets encountered range and fueling-infrastructure constraints. The X15N's cost performance in a year without federal ZEV subsidies suggests the engine crossed into TCO territory that works independent of policy tailwinds.

What happened to federal zero-emission truck incentives?

The rollback of greenhouse gas vehicle standards, expiration of commercial zero-emission vehicle tax credits worth up to $40,000 per medium- and heavy-duty unit, and nullification of California's clean truck regulations removed the federal policy framework that had driven ZEV orders from 2022 through early 2025. Fleet managers who had spec'd electric trucks to capture tax credits or meet California mandates now face order decisions without either carrot or stick.

Despite the federal retreat, available funding for clean projects still exceeds pre-Biden levels. More than $5 billion flows annually from state, local, and utility programs through 2028. California alone held roughly $1 billion in grants for on-road trucks and buses last year and reserved $592 million in vouchers for 3,569 Class 2b-8 zero-emission vehicles through its Hybrid and Zero Emission Truck and Bus Voucher Incentive Project.

Are battery-electric trucks still gaining registrations?

Medium- and heavy-duty battery-electric vehicle registrations rose 21% in 2025. Fleets operating medium-duty BEVs reported lower operating costs than the vehicles they replaced — a result that mirrors the X15N's cost performance and points to a shift from compliance-driven orders to economics-driven adoption.

The 21% registration increase occurred during a prolonged freight recession that suppressed new vehicle orders across every drivetrain. Tariff disruptions and regulatory reversals compounded the uncertainty. The fact that BEV registrations grew in that environment suggests medium-duty electric trucks have reached a TCO threshold that works for specific duty cycles — last-mile delivery, urban distribution, predictable daily mileage — even without federal subsidies.

What fuel is displacing diesel in California?

Renewable diesel and biodiesel displaced nearly three-quarters of conventional diesel in California's transportation market in 2024. The displacement rate reflects California's Low Carbon Fuel Standard credits and the state's renewable-fuel infrastructure, which matured faster than charging or hydrogen networks. For fleets running California lanes, renewable diesel offers a drop-in fuel that requires no equipment changes and delivers immediate carbon-intensity reductions without the range or payload compromises of battery-electric or hydrogen trucks.

The renewable-diesel share also explains why California's $1 billion in on-road truck grants did not translate into proportional ZEV orders — fleets could meet carbon targets with existing equipment by switching fuel suppliers.

What this means for small fleets ordering trucks in 2026

Fleets ordering trucks in 2026 face a diversified menu with no single policy-driven answer. Natural gas makes sense where fuel-price spreads favor CNG or LNG and where fueling infrastructure exists along the route. Battery-electric works for medium-duty urban routes with predictable mileage and depot charging. Renewable diesel works for California fleets running conventional equipment. Diesel remains the default for long-haul and for fleets without access to alternative-fuel infrastructure.

The X15N's 71% cost-savings figure and the 21% BEV registration increase both occurred in a year when federal incentives disappeared — a signal that the equipment has crossed into territory where operating economics, not policy compliance, drive the order. For small fleets and owner-operators, that shift matters more than any single regulation or tax credit. The question is no longer whether alternative drivetrains can work; it is whether the duty cycle, fuel availability, and TCO math line up for the next truck on order.