The change takes effect at once and reaches every model year not yet billed
What the document says“The amendments made by subsection (a) shall-- (1) take effect on the date of enactment of this section; and”
The section provides that the amendments take effect on the date of enactment and apply to all model years of a manufacturer for which the Secretary of Transportation has not yet given notice under section 32903(b)(2)(B) of title 49, United States Code specifying the penalty due for falling below the applicable standard under section 32902 of that title.
What the document actually says“The amendments made by subsection (a) shall-- (1) take effect on the date of enactment of this section; and”
The changes start at once. That is the day this part becomes law.
They also reach back to earlier model years. That holds where the government has not yet sent a bill. Once a bill has gone out, the change does not apply.
No action is recorded against this proposal. That is not evidence that none has been taken, and nobody has yet read it against the record. See what the tracker does not yet cover.