Evolving Clean Fleet Rules in Other States Underscore Challenges for Local Governments

Recent developments in Massachusetts and Maryland reveal the growing difficulties states are facing in enforcing clean fleet regulations modeled after California’s Advanced Clean Fleets (ACF) program. These policy shifts may further constrain the already limited availability of zero-emission medium- and heavy-duty vehicles that California counties are required to purchase under state law. 

On April 17, the Massachusetts Department of Environmental Protection (MassDEP) announced it will exercise enforcement discretion for manufacturers unable to meet electric truck sales requirements under the state’s Advanced Clean Trucks (ACT) rule. This regulatory pause will apply to Model Years 2025 and 2026, allowing manufacturers to continue selling internal combustion engine (ICE) trucks as long as they remain available to distributors.  

Maryland is taking similar steps. Earlier this month, Maryland Governor Wes Moore issued Executive Order 01.01.2025.10, directing the Maryland Department of the Environment to delay enforcement and waive penalties for manufacturers who fall short of ZEV sales requirements under both the ACT and Advanced Clean Cars II programs. The Executive Order also establishes a statewide working group to assess implementation challenges and develop recommendations for successful deployment of clean vehicle programs.  

These delays reflect a key reality facing states across the country: vehicle manufacturers are not yet able to meet mandated ZEV sales quotas due to slow market adoption, supply chain constraints, and changing federal policy, including uncertainty around tariffs and infrastructure funding. 

Implications for California Counties 

California local governments are under increasing pressure to comply with the state’s ACF regulation, which mandates the purchase of ZEV medium- and heavy-duty vehicles on strict timelines. As other states adjust timelines and enforcement practices, California counties may face even greater challenges accessing compliant vehicles. Reduced demand in other states could slow production and distribution, further constraining supply in California. 

In response to these challenges, CSAC – alongside other local government partners – is sponsoring Senate Bill 496, authored by Senator Melissa Hurtado, to bring much-needed flexibility to the ACF mandate. SB 496 would provide common-sense reforms, including the creation of an ACR appeals advisory committee to offer local agencies a formal process to challenge exemption denials, thereby ensuring transparency and due process. The bill would also update the emergency vehicle exemption so that vehicles involved in emergency and disaster response can continue to operate, and would revise the daily usage exemption to ease unnecessary burdens. 

While California continues to lead in climate policy, the recent actions in Massachusetts and Maryland highlight the importance of maintaining flexibility, monitoring market conditions, and ensuring that county governments are equipped with realistic pathways to compliance.