EPA releases MOVES6 vehicle emissions model, starting two-year conformity grace period

The U.S. Environmental Protection Agency (EPA) on Oct 27 announced the availability of MOVES6, its latest motor vehicle emissions model, starting a two-year grace period before the model is required for new transportation conformity analyses outside California.

MOVES6 estimates emissions from cars, trucks, buses and motorcycles. It is available for state implementation plans (SIPs) and transportation conformity analyses in states other than California, according to the notice.

EPA said it is releasing MOVES6 to account for the Endangerment Finding Rescission Rule, finalized on Feb. 12, 2026, which repealed all greenhouse gas emission standards for light-, medium- and heavy-duty on-highway vehicles and engines.

The model also accounts for Congress's disapproval of the waiver for California's Advanced Clean Trucks regulations and for legislation that reduced incentives for electric vehicles and charging infrastructure, the agency said.

MOVES6 still projects that some vehicles are electric in future years, but those fractions are generally smaller than in MOVES5 and MOVES4, according to the notice.

Transportation conformity is meant to ensure that federally funded or approved highway and transit activities are consistent with the purpose of a SIP. Under the notice, modelers who start new analyses with MOVES5 during the grace period must update its electric vehicle projections or use MOVES6.

For SIPs, there is no grace period. EPA said MOVES6 should be used "as expeditiously as possible." States that have already completed significant work with MOVES5 or MOVES4 may continue to rely on those versions.

EPA said it does not require states to revise submitted or approved SIPs because a new model is available.

The grace period for MOVES5, set in December 2024, is unchanged and remains in effect until Dec. 11, 2026, the notice said.