New EPA rules would cut car emissions 56% by 2032

On Wednesday, after a week of rumors and anticipation, the US Environmental Protection Agency published proposed new vehicle emissions regulations. If adopted, the new rules would go into effect for model years 2027–2032 and would be the strictest fuel economy regulations yet seen in the United States, cutting fleet carbon emissions for light-duty vehicles by 56 percent from 2026 levels.

The new regulations would also bring in tougher standards for other airborne pollutants emitted by the internal combustion engines in those light-duty vehicles. Additionally, the EPA proposes tougher new rules on medium-duty (class 2b and class 3) vehicles—mostly large pickup trucks and vans with a gross vehicle weight rating of 8,501–14,000 lbs. The EPA is also looking to modify some credit programs and wants new durability and warranty standards for the battery packs in battery electric vehicles.

The EPA thinks that two-thirds of new car sales will be electric within the next decade if the rules are adopted, as they require automakers to sell many more BEVs.

152 g CO₂/mile

The EPA regulations continue to make distinctions between passenger cars and trucks (which includes vans and SUVs) when it comes to light-duty vehicles. It does note that most light-duty vehicles only carry passengers and do not tow or haul, and the agency will continue to give light trucks more lenient emissions regulations, which factor in offsets for all-wheel drive and utility that increases with a vehicle’s footprint.

The proposed rules do also acknowledge that OEMs have taken advantage of similar leniency in the past to reclassify light-duty vehicles as light trucks in order to pollute more. One way the EPA hopes to prevent that is by increasing the minimum allowed footprint for a car from 41 square feet to 45 square feet by model year 2032 and by reducing the maximum footprint of trucks to 70 square feet (from 73 square feet) by model year 2030.

As you might expect, the CO₂ targets are a bit tougher for more efficient cars to hit than trucks, as shown in the following table:

For the fleet averages, the EPA is assuming a mix of 40 percent cars to 60 percent trucks for model years 2026–2029 and 41 percent cars to 59 percent trucks from model year 2030 onward.

The proposed targets for medium-duty vehicles allow these vehicles to emit much more carbon dioxide from their tailpipes, and less aerodynamic pickup trucks are allowed to pollute more than vans, as you can see from the following table:

For medium-duty vehicles, the EPA is proposing eliminating the multiplier credits it previously gave to electrified medium-duty vehicles as a result of the rapid increase in electrification of these vehicles in the past few years.

There are other pollutants, too

The EPA doesn’t just care about carbon emissions; it also wants to decrease the amounts of “non-methane organic gases and nitrogen oxides,” or NMOG+NOx, as well as particulate matter, carbon monoxide, and formaldehyde. Rather than just adopting these new standards as is, the agency proposes eight phase-in scenarios it will let automakers pick from.

That makes it a little complicated to break down how much or how little each model year is supposed to pollute, but for NMOG+NOx, the EPA is targeting 12 mg/mile for light-duty vehicles and 60 mg/mile for medium-duty vehicles by model year 2032. Particulate matter would be capped at 0.5 mg/mile.

There are different carbon monoxide caps based on ambient temperatures. At 25˚C, light-duty vehicles will be allowed to emit 1.7 g/mile, but 10 g/mile at -7˚C. Formaldehyde emissions will be capped at 4 mg/mile. For medium-duty vehicles, the caps for carbon monoxide are 3.2 g/mile at 25˚C and 10 g/mile at -7˚C, and 6 g/mile for formaldehyde.

That battery better last

Obviously, none of the above emissions rules will have much effect on a battery EV since they emit no tailpipe emissions; the EPA says it will continue to regulate emissions from electricity generation separately, and it’s therefore not appropriate to factor that into rating EV efficiency.

That’s not to say the proposed rules don’t affect EVs—the new regulations include battery durability and warranty requirements for both light- and medium-duty battery EVs and plug-in hybrid EVs. This would require automakers to include a battery state-of-health monitor in new EVs that would easily tell the vehicle’s owner how much useable battery energy the pack can store as a percentage of the original usable battery energy.