California Air Resources Board

The Need for More Stringent Motorcycle Regulations

On May 17, 2016, the California Air Resources Board (CARB) released for public review and comment the Proposed 2016 State SIP Strategy, describing proposed measures to achieve the reductions necessary from the mobile sector and consumer products to meet federal ozone and PM2.5 standards over the next 15 years.  Regulatory measures represent a comprehensive and aggressive scope of action across all sectors and account for approximately 70 percent of emission reductions anticipated from the State SIP Strategy measures.  Deployment of cleaner technologies, such as Zero-Emissions Vehicles (ZEVs) will achieve the remaining reductions.

On May 16, 2016, the California Air Resources Board (CARB) released the updated Mobile Source Strategy, which demonstrates how the state can achieve goals of reducing emissions from mobile sources, including an 80 percent reduction of smog-forming emissions in the south coast and a 45 percent reduction in Greenhouse Gas (GHG) emissions statewide.  It is important that CARB prioritize mobile source categories for which the most cost effective emission reductions can be achieved. 

Historically On-Road Motorcycles (ONMCs) have only accounted for a small fraction of all mobile source emissions.  However, as emissions from passenger cars continue to decrease, motorcycles become a larger part of the overall emissions inventory.  If left alone, Reactive Organic Gas (ROG) emissions from this category are projected to nearly match those of passenger cars by the year 2035, despite making up a small percentage of on-road vehicles and miles traveled.

Potential Harmonization with European Union Standards

ONMCs are a mobile sources category for which more stringent emissions standards are easily achievable.  Advanced emissions control technologies from passenger cars are readily available.  While there are challenges involved, some of these technologies can be scaled down for use in ONMCs.  The European Union (EU) has already adopted more stringent standards, requiring manufacturers to comply with the Euro 4 standards in 2016, and Euro 5 standards starting in 2020.  The Euro 5 Effects Study was conducted to investigate the feasibility and cost effectiveness of this emissions control technology implementation.

CARB is considering harmonizing with the Euro 5 standards in order to obtain these potentially cost effective emissions reductions.  However, there are challenges involved with harmonization, including understanding Euro 5 differences from current CARB testing and certification procedures.  A more detailed discussion of the challenges related to harmonization was given in the April 2018 ONMC workshop presentation.

CARB is currently working with manufacturers and stakeholders through Technical Working Groups (TWG) to address concerns relating to ONMC regulatory development and challenges related to harmonization with EU standards. 

Comprehensive Regulatory Proposal Elements

In addition to updating emissions standards to reflect the European Euro 5 emissions limits, CARB is also planning to propose the following elements:

• New evaporative test procedures to reflect real world motorcycle usage.
• More stringent evaporative emission standards to further reduce smog-forming emissions.
• On Board Diagnostics (OBD) to identify malfunctions in emissions controls and encourage timely repairs.
• New durability requirements to ensure emissions control components function as intended for the useful life of the vehicle.
• Requirements to accelerate development and widespread adoption of zero emissions motorcycles (ZEMs), starting in 2028 and increasing to 50% of new motorcycle sales in 2035.

Regulatory Development and Implementation Timeline

• November 28, 2023:  45-day public comment period on staff regulatory proposal. (Click here to review the staff proposal and supporting documentation.)
• January 25, 2024: Board Hearing to consider proposed ONMC regulatory update. (Click here to view the Board Hearing Agenda and webcast)
• Model Year 2024: Begin awarding zero-emission motorcycle credits on a voluntary basis.
• Model Year 2028: Begin phase-in of new emission standards and test procedures.

This rulemaking timeline is tentative and subject to change. For more information on past and upcoming public workshops, please visit our Meetings & Workshops page, and subscribe to our e-mail announcement service. If you have any questions or would like more information regarding CARB's current regulatory development process for ONMC, please contact Jason McPhee at (279) 208-7023.