Emissions standards

Current understanding

To be populated as evidence accumulates.

Evidence log

• 2026-08-31 — Resetting NHTSA’s Fuel Economy Program: Commercial Medium- and Heavy-Duty On-Highway Vehicles and Work Trucks: cross-connection with nhtsa-mdhd-fuel-economy: NHTSA’s fuel-economy program for heavy-duty vehicles has historically been coordinated with EPA greenhouse-gas/emissions standards; narrowing NHTSA’s scope to whole vehicles (excluding engines) creates a gap relative to EPA’s engine-level regulatory approach. (novelty: 3)
• 2026-07-23 — Providing congressional disapproval under chapter 8 of title 5, United States Code, of the rule submitted by the Environmental Protection Agency relating to “California State Motor Vehicle Pollution Control Standards; Notice of Decision Granting a Waiver of Clean Air Act Preemption for California’s Advanced Clean Car Program and a Within the Scope Confirmation for California’s Zero Emission Vehicle Amendments for 2017 and Earlier Model Years”.: 2025 — H.J.Res. 205 introduced as a Congressional Review Act joint resolution to disapprove EPA’s waiver of Clean Air Act preemption for California’s Advanced Clean Car Program and the within-scope confirmation for its Zero Emission Vehicle amendments (2017 and earlier model years); companion to the ACC II disapproval, targeting the earlier waiver decision. (novelty: 2) (novelty: 2)
• 2025-06-12 — Providing congressional disapproval under chapter 8 of title 5, United States Code, of the rule submitted by the Environmental Protection Agency relating to “California State Motor Vehicle and Engine Pollution Control Standards; Advanced Clean Cars II; Waiver of Preemption; Notice of Decision”.: Public Law 119-16 (CRA joint resolution) disapproved and nullified EPA’s waiver granting California authority to enforce its Advanced Clean Cars II low-emission and zero-emission vehicle standards, removing the federal preemption exception for that program. (novelty: 3)

Open questions

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