Massachusetts and Maryland, two of the 10 states that adopted California's Advanced Clean Truck (ACT) rule, have now delayed enforcement of the stringent emissions targets, reported OPIS.

The rule requires manufacturers of on-road medium- and heavy-duty vehicles to produce and sell an increasing percentage of zero-emission vehicles (ZEV) from model years 2025 through 2035. ZEV technology encompasses primarily battery electric vehicles (BEV) and, to a lesser extent, fuel cell electric vehicles (FCEV). Lower-emission alternative fuels compatible with today’s internal combustion technology, like biofuels and synthetic fuels, do not qualify as ZEV under the regulations.

“The Massachusetts Department of Environmental Protection (MassDEP) on Tuesday announced a two-year reprieve for truck manufacturers unable to meet the requirements of the Advanced Clean Trucks program. Manufacturers will get a grace period for the 2025 and 2026 model years if they continue to make internal combustion engine (ICE) trucks for distributors,” wrote OPIS. “And Maryland Gov. Wes Moore earlier this month signed an executive order suspending enforcement of the ACT program for two years.”

MassDEP said that truck manufacturers find the regulation too difficult. Some manufacturers are limiting ICE truck sales to ensure they comply with the sales requirements.

The department also said the Trump administration created “significant uncertainty around ZEV incentives, charging investments, manufacturing and tariffs, each of which threaten a smooth transition to medium- and heavy-duty ZEVs.”

The ACT delay gives manufacturers “flexibility” while keeping Massachusetts “on track” to achieve emissions reductions, MassDEP said.

This delay comes as NACS continues advocating to overturn the California mandates at the federal level. NACS and its cosigners previously sent a letter to Congress asking it to review the U.S. Environmental Protection Agency (EPA) waivers that enabled California and other states to adopt the ACT regulations.