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US EPA proposes emission standards for MY 2027 light-duty vehicles, Phase 3 GHG standards for heavy-duty vehicles

12 April 2023

The US Environmental Protection Agency (EPA) announced new proposed federal vehicle emission standards for model year (MY) 2027 and later light- and heavy-duty vehicles. The proposed standards are described in two proposed rules:

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Light- and Medium-Duty Vehicle Proposed Standards. The first set of proposed standards, the “Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium Duty Vehicles,” would bring new, more stringent emission standards for criteria pollutants and GHGs for light-duty vehicles and Class 2b and 3 (“medium-duty”) vehicles that would phase-in over model years 2027 through 2032.

The light-duty CO2 standards continue to be footprint-based, with separate standards curves for cars and light trucks. The EPA is proposing to revise the footprint standards curves to flatten the slope of each curve and to narrow the numerical stringency difference between the car and truck curves. The medium-duty vehicle standards continue to be based on a work-factor metric designed for commercially-oriented vehicles, which reflects a combination of payload, towing and 4-wheel drive equipment.

The proposed GHG standards are projected to accelerate the transition to electric vehicles. The EPA projects that in MY 2032, EVs could account for 67% of new light-duty vehicle sales and 46% of new medium-duty vehicle sales.

The key changes to the criteria pollutant emission standards are:

The EPA projects that the new PM standards will drive widespread use of filters to reduce gasoline particulate matter emissions and the GHG standards will spur greater deployment of CO2-reducing technologies for gasoline-powered vehicles.

In addition, the EPA has proposed GHG program revisions in several areas, including off-cycle and air conditioning credits, the treatment of upstream emissions associated with zero-emission vehicles and plug-in hybrid electric vehicles in compliance calculations, medium-duty vehicle incentive multipliers, and vehicle certification and compliance. The EPA has also proposed new standards to control refueling emissions from incomplete medium-duty vehicles, and battery durability and warranty requirements for light-duty and medium-duty plug-in vehicles.

A separate regulation, proposed by the Department of Energy (DOE), would also change the methodology for the calculation of CAFE petroleum-equivalent fuel economy ratings for electric vehicles, beginning with MY 2027. The old fuel economy method divided the EV electricity consumption converted to gasoline equivalent by a constant coefficient of 0.15. The concern was that the method was making EVs look cleaner than they really are, thus allowing manufacturers to continue selling more polluting ICE vehicles. The proposed new method, based on life-cycle approach for electricity production, would produce lower EV fuel economy values, making it harder for manufacturers to meet CAFE standards by increasing the EV share in their vehicle fleet.

Heavy-Duty Truck Proposed Standards. The second set of proposed standards, the “Greenhouse Gas Standards for Heavy-Duty Vehicles - Phase 3,” would apply to heavy-duty vocational vehicles (such as delivery trucks, refuse haulers or dump trucks, public utility trucks, transit, shuttle, school buses) and trucks typically used to haul freight. These standards would complement the criteria pollutant standards for MY 2027 and later heavy-duty vehicles that the EPA finalized in December 2022.

The proposed program features several key provisions that include updating the existing MY 2027 GHG emission standards and promulgating new GHG emission standards starting in MY 2028 through 2032 for HD vehicles. Specifically, the EPA is proposing to set progressively more stringent GHG emission standards that would apply to MY 2027, 2028, 2029, 2030, 2031, and 2032.

The proposed standards do not mandate the use of a specific technology, and the EPA anticipates that a compliant heavy-duty fleet would include a mix CO2-reducing technologies such as transmission technologies, aerodynamic improvements, engine technologies, battery electric powertrains, and hydrogen fuel cell powertrains.

The EPA plans to hold virtual public hearings for both proposed rules—on May 2 and 3 for the heavy-duty Phase 3 rule and on May 9-10 for the light-duty proposal. Public comments on the proposals must be received within 60 (light-duty rule) or 50 (heavy-duty rule) days after the date of publication in the Federal Register.

Source: US EPA