Navigating CARB’s Latest Low NOx Engine Standards for Fleet Managers

Fleet Managers Face New Reality as CARB’s Low NOx Engine Standards Transform California’s Commercial Vehicle Landscape

The landscape of fleet management in California has undergone a dramatic transformation with the implementation of CARB’s latest Low NOx engine standards. The California Air Resources Board (CARB) adopted the amended Omnibus Low NOx regulation in September 2021, which established more stringent NOx and Particulate Matter standards applicable to new 2024 and later Model Year medium- and heavy-duty diesel engines, mandating a 75% reduction in NOx emissions and a 50% reduction in particulate matter (PM) from heavy-duty on-road engines for engine model years 2024 through 2026.

Understanding the New Standards

The rule tightened FTP NOx limits to 0.050 g/bhp·hr from 2024 and to 0.02 g/bhp·hr from 2027, introduced a new LLC certification cycle and a corresponding set of NOx limits, and extended emission durability requirements to 800,000 miles. For fleet managers, this represents a significant shift from previous standards and requires immediate attention to compliance strategies.

The regulations apply to medium-duty engines (used in vehicles from 10,001 to 14,000 pounds GVWR) and heavy-duty engines (used in vehicles over 14,000 pounds GVWR), with engine idling provisions extended to medium-duty engines. This broad scope means that virtually all commercial fleets operating in California must adapt to these new requirements.

Compliance Challenges and Solutions

Fleet managers are discovering that manufacturers are not introducing sufficient engines compliant with these MY 2024 standards, affecting fleet options to buy new trucks, as OEMs have deferred any plans to introduce new engines meeting MY 2024 – 2026 standards. However, CARB has provided some flexibility to ease this transition.

The original standard provides some flexibility for OEMs to sell heavy-duty diesel engines (HDDEs) compliant with current NOx standards (0.2 g/bhp-hr), so called “legacy” engines, capped at 45% and 25% of each OEMs sale in California, in MY 2024 and 2025 respectively, with exceedence in NOx emissions required to be offset by using HD zero-emission credits, combustion credits, or projects in disadvantaged communities.

Fleet Transition Strategies

The Advanced Clean Fleets (ACF) regulation adds another layer of complexity for fleet managers. Beginning January 1, 2024, State and local government fleets are required to add ZEVs to the fleet as a percentage of their purchases each year, with 50% of vehicle purchases required to be zero-emission vehicles starting January 1, 2024, and 100% of purchases must be zero-emission starting January 1, 2027.

For commercial fleets, High Priority Fleets must comply with the Model Year Schedule starting January 1, 2024, and may only add ZEVs to their California fleet, while starting January 1, 2025, must remove internal combustion engine vehicles that have exceeded their useful life as specified in the regulation.

Engine Manufacturer Response

Major engine manufacturers are adapting to these requirements with varying degrees of success. In 2024, PACCAR launched their CARB-compliant PACCAR MX-13 engine for select Class 8 models, including the T680, T880 and W990, available in 510-HP/1,850 lb.-ft of torque and 455-HP/1,650 lb.-ft of torque ratings. Similarly, Volvo’s CARB 24-compliant engine is available for order now in the VNR and current VNL models with a power rating of 455 HP and 1650 lb.ft. of torque.

The Path Forward

CARB reached an agreement with the Truck and Engine Manufacturers Association (EMA) in July 2023, known as the Clean Truck Partnership (CTP), that committed CARB to propose amendments to the Omnibus regulation that would generally align the emissions standards with the corresponding provisions in the federal EPA-NOx rule, with amendments proposed in March 2024 and scheduled to be finalized in late 2025.

For fleet managers operating in California, ensuring compliance with these evolving regulations requires working with certified testing facilities. When it comes to maintaining compliance with emissions standards, partnering with experienced providers for CARB Compliance Glendale, CA services becomes essential for fleet operations.

Practical Steps for Fleet Managers

Fleet managers should take several immediate actions to ensure compliance:

RV manufacturers should be making certain that any heavy-duty diesel engine-equipped motorhome being shipped to California has the required labels attached, and RV dealers should be certain that any diesel motorhome being sold by their dealership contains the needed labels if the engine is from model year 2024 or later to avoid the consumer having any issues with titling and registration.

The transition to CARB’s Low NOx standards represents both a challenge and an opportunity for fleet managers. While the immediate compliance requirements may seem daunting, these regulations are driving innovation in engine technology and creating a cleaner, more efficient future for commercial transportation. Success in this new regulatory environment requires proactive planning, strategic partnerships, and a commitment to staying ahead of evolving standards.