The California Air Resources Board (CARB) released its Second 15-Day Notice of Modifications to the Advanced Clean Fleets (ACF) regulation on June 1, 2026, advancing the rulemaking process while leaving key stakeholder concerns unresolved.

Notably, CARB staff has doubled down in this draft on its interpretation that private companies operating under contract for state and local government (SLG) entities are considered part of those entities’ fleets—and therefore subject to ACF—maintaining that these revisions reflect the original intent of the regulation rather than a major policy shift.

However, this latest draft does not substantively address the concerns raised by more than 200 opposition commenters during the prior comment period. Many stakeholders including CRTA had urged CARB to reconsider the inclusion of private contractors under the state and local government fleet requirements, citing significant operational and compliance challenges.

The public comment period for the Second 15-Day Changes is open through June 16, 2026. Stakeholders are encouraged to review the updated regulatory language and submit feedback before the deadline. Click here for more information.