NHTSA's June 2025 interpretive rule on CAFE: the agency's new reading of 49 U.S.C. 32902(h)

On June 11, 2025, the National Highway Traffic Safety Administration published an interpretive rule in the Federal Register titled "Resetting the Corporate Average Fuel Economy Program." The document carries the citation 90 FR 24518, runs ten pages (24518-24527), and amends nothing by itself: the agency's action line reads "ACTION: Interpretive rule." An interpretive rule states how the agency reads the statute it administers; it does not, on its own, set new fuel economy numbers. The document covers 49 CFR Parts 531, 533, and 535, the parts of the Code of Federal Regulations associated with the US passenger car and light truck CAFE program.

The rule's effective date is stated plainly in the DATES section: "This interpretive rule is applicable as of June 11, 2025." That is the date the interpretation takes effect, not the date any new standards are finalized. The document's own table of contents points to a section on "Next Steps in Resetting the CAFE Program and Enforcement Considerations," signaling that the reset of the CAFE program is a process this rule begins to frame rather than one it completes. Comments on this document are closed: the Federal Register page notes that comments are no longer being accepted.

What the rule reinterprets

The core of the document is Section II, headed "Interpretation of Statutory Limitations in 49 U.S.C. 32902(h) as Applied to NHTSA's Standard-Setting Analysis." Section 32902(h) of title 49 of the United States Code contains limitations Congress placed on how NHTSA may set CAFE standards. The rule affirms that NHTSA "cannot consider the section 32902(h) factors for any purpose and at any point in the process of setting fuel economy standards." Its table of contents breaks the interpretation into three subsections:

• Improper Consideration of Dedicated Alternative Vehicle Fuel Economy
• Improper Consideration of Dual-Fueled Vehicle Fuel Economy
• Improper Consideration of Compliance Credits

On dedicated alternative-fuel vehicles, the rule quotes subsection (h)(1) directly: the Secretary "may not consider the fuel economy of dedicated automobiles." On dual-fueled vehicles, it cites subsection (h)(2), which states that NHTSA "shall consider dual fueled automobiles to be operated only on gasoline or diesel fuel." On credits, the rule says the fuel economy standards the agency establishes "must be feasible and practicable for gas-powered vehicles without regard to any reliance on non-gas-powered alternatives or compliance credits." The rule also faults the earlier treatment of dual-fueled vehicles outside standard-setting years as "inconsistent with a plain reading of section 32902(h)."

Section III of the rule is titled "CAFE Program Regulations Based on the Best Reading of the Underlying Statute Would Minimize Market Distortion," and Section IV addresses "Interpretation of Statutory Authority and Requirements Applicable to the MDHD Program" — the medium- and heavy-duty vehicle provisions. On the MDHD program, the rule states that NHTSA considered credits and EVs "without express authority to do so and in contrast with the explicit limitations applicable to the CAFE program in section 32902(h)," and that NHTSA "will engage in rulemaking to reconsider the standards established for the MDHD program."

Why an interpretive rule matters

Because an interpretive rule changes the agency's reading of its statutory authority rather than the numbers themselves, its practical effect arrives through what follows. A CAFE reset would be a separate rulemaking, and this document's structure — background on Congress's limits on the 32902(h) factors, the interpretation, the MDHD authority, and a next-steps section — reads as the groundwork for that process. For manufacturers selling in the United States, the treatment of dual-fueled vehicles and credits affects compliance calculations under the program; the rule itself states that any costs and benefits of the forthcoming rules "will be analyzed in those rulemakings," which we have not read and cannot summarize here.

How to verify this yourself

• Read the Federal Register entry for Docket No. NHTSA-2025-0055 (document number 2025-10586), dated June 11, 2025; the web rendition is explicitly unofficial, and the site advises verifying contents against a final, official edition for legal research.
• Check the SUMMARY and DATES sections for the rule's operative scope and effective date, and the table of contents for where each interpretation is argued.
• Track subsequent NHTSA rulemakings on regulations.gov under the same docket to see whether a reset proposal has actually been published before treating any new standard as in force.