State Action on Clean Vehicles is More Crucial Than Ever

EPA’s recent announcement to cut tailpipe pollution for light, medium, and heavy-duty vehicles is an important step, but the Advanced Clean Trucks (ACT), Advanced Clean Cars II (ACC II), and Heavy-Duty Omnibus (HDO) rules are still critical policies to achieving our climate goals and should be adopted by states. 

Semi-Truck on residential street

Medium- and heavy-duty trucks idle on a residential street 

On April 12, the US EPA took a significant step to clean up the transportation sector and released two proposals to set new tailpipe emission standards for passenger cars, deliver vans and trucks, and heavier duty trucks. While these rules are a step in the right direction to curb greenhouse gas emissions from transportation and may complement other state efforts, they are not a replacement for strong state standards like the Advanced Clean Trucks (ACT), Heavy-Duty Omnibus (HDO), and Advanced Clean Cars II (ACC II) rules. Think of it like this. The federal standards set a baseline for emissions that may increase the overall supply of clean vehicles as manufacturers produce more to meet the EPA rules “fleet average” emission requirements; state standards go further by requiring a certain percentage of clean vehicles be sold in each state annually. All states will benefit from the reduced tailpipe emissions from the federal rules, but only by adopting the state standards can a state guarantee that zero-emission vehicles will be available for purchase in their state, locking in significant emission reductions and increasing consumer choice of clean vehicles.  

Transportation in the United States generates the largest share of greenhouse gas emissions, primarily from burning fossil fuels (diesel, gasoline, and natural gas) for our cars and trucks. The impacts of this pollution are not felt evenly; communities and workers within and near high-traffic locations, such as rail yards, warehouses, industrial corridors, and highways see significantly more tailpipe pollution, which are linked to serious public health concerns. My home state of Illinois, currently considering adopting advanced vehicle policies, ranks fifth among all states with the highest number of deaths from diesel engine pollution per capita in 2023. 

States are Leading on Clean Cars

The 18 states that have completely or partially adopted the Clean Cars rules have done so to significantly improve air quality and health while doing their part to reduce greenhouse gas emissions. Collectively, these states represent 40% of new vehicle sales in the country, an enormous share of the overall vehicle market.  The ACC II rule is feasible - automakers have shown that they can deliver zero emission vehicles and states have taken note, adopting standards that will get EVs on the road.  

The ACC II rule creates a market and a consistent supply of ZEVs within a state, ensuring states can meet their climate and air quality goals in the next two decades. The federal rule focuses on GHG emissions and due to the stringency of the rules, EPA anticipates the rule will increase the national sales of new EVs to about 67% by 2032 as automakers produce more ZEVs to meet the tailpipe emission standards. EPA also anticipates a 56% reduction in GHG emissions from the national light-duty fleet sold in 2032. While this is a great step to reducing emissions and may increase the overall light-duty ZEVs available across the country, there is no guarantee that those ZEVs will make it to a specific state.  

The best way for states to ensure passenger ZEVs reach their state (automakers are likely to send new vehicles to ACC II markets before others), and to insulate themselves from the effects of political changes at the federal level, is to adopt the ACC II rule. 

 ACC II ensures that by 2032, 84% of new vehicle sales in the adopting state will be zero-emission and that by 2035, 100% of new vehicle sales will be ZEVs. An independent study published for New York’s adoption of ACC II shows a 96% reduction in GHG emissions compared to the baseline for the state. There is no guarantee that the federal rule will remain as strong as proposed, or that manufacturers will produce and sell more ZEVs in a specific state because of the federal standards. By adopting ACCII, states can provide certainty and stability to utilities and relevant industries working in the state that are actively investing in and preparing for this transition. It also guarantees states grow their ZEV market while ensuring they quickly and effectively reduce emissions from light-duty vehicles.  

EPA Rule Falls Further Behind on Clean Trucks

Like the ACCII rule, the Advanced Clean Trucks rule creates a consistent supply of zero-emission trucks and buses within a state. This includes a range of vehicles from large pickup trucks and delivery vans to long-haul trucks. The ACT rule gradually ramps up ZEV sales as a percentage of total medium and heavy-duty vehicle sales, eventually resulting in 40-75% ZEV sales depending on vehicle size by 2035. The federal rule only focuses on reducing GHG emissions from tailpipes, and while it may incentivize the sale of ZEVs to meet fleetwide emission requirements, it also incentivizes the use of alternative combustion technologies which may reduce GHG emissions but are not nearly as effective as ZEVs at reducing emissions from “source to tailpipe to grave.” States interested in getting more ZEVs on the road and reducing their overall dependence on fossil fuels should adopt the ACT rule. 

Just looking at the numbers for Class 4-8 vehicles (including delivery vans up to garbage trucks and semi-trucks), EPA estimates their regulation would increase the ZEV sales of those vehicles by about 44% nationally by 2032. This compares to 60% ZEVs as a portion of new vehicle sales by 2032 under the ACT rule, with the guarantee those vehicles will be available in your state.  

We already know that federal standards under this administration have the potential to fall short of strong and feasible state emission standards. Last year, EPA had a chance to finalize strong truck standards and reduce the amount of health-harming and smog-forming pollutants emitted by large trucks and buses. Ultimately, the final rule fell short, largely due to a well-orchestrated lobbying effort by truck manufacturers and other critics of heavy-duty vehicle emission standards. As a result of weaker standards at the federal level, states must adopt the Heavy-Duty Omnibus rule to ensure their communities are protected from diesel truck emissions to the greatest extent possible.  

With all of this in mind, state decision-makers should not hit the brakes (forgive me) on state level standards. Zero-emission cars and trucks are the fastest way to curb GHG emissions from the transportation sector. Truck and automakers have shown they can deliver zero-emission vehicles, and states should continue leveraging the historic federal investments under the Inflation Reduction Act and the Bipartisan Infrastructure Law to facilitate the transition. Strong state standards paired with incentives and rebates allow states to go even further than the EPA, securing an equitable and environmentally just future for their residents, regardless of the federal government passing a strong emission standard.  

Stay tuned for further updates on the rules from our experts, including analyses on impacts of the EPA regulations and how they can be improved.  

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