Incorporated Regulations

9. Incorporated Regulations#

EMFAC2025 v2.0.0 was officially released on May 14, 2025. Following its release, three unlawful Congressional resolutions purported to disapprove the U.S. EPA’s prior actions to grant California waivers for several regulations incorporated in the model, including:

  • Advanced Clean Cars II (ACC II)

  • Advanced Clean Trucks (ACT)

  • Zero-Emission Airport Shuttle

  • Heavy-Duty Vehicle and Engine Emission Warranty and Maintenance Provisions (Warranty Phase 1)

  • Heavy-Duty Omnibus (Omnibus)

While the congressional actions are being contested, EMFAC2025 v2.1.0 has been released to reflect the current regulatory conditions. This version removes the emissions benefits of the above regulations that were included in EMFAC2025 v2.0.0. These actions also affect the emissions benefits from regulations implemented in EMFAC2021 v1.0.2; consequently, Sections 4.6.3, 4.6.4, 4.6.5, and 4.6.6 of the EMFAC2021 Technical Documentation (CARB, 2021) are no longer applicable to EMFAC2025.

Following the removal of Omnibus’ emissions benefits, CARB staff assumed that California-certified engines of model year 2027 and newer would meet the Federal Clean Trucks Plan requirements, as further described in Section 9.3.

EMFAC2025 v2.1.0 also removes the Federal Phase 3 Greenhouse Gas Emissions Standards (U.S. EPA, 2024) and the Multi-Pollutant Emissions Standards for Model Years 2027 and Later Light-Duty and Medium-Duty Vehicles (U.S. EPA, 2024), both of which were repealed in February 2026.