Section 537.8 - Supplementary reports(a)(1) Except as provided in paragraph (d) of this section, each manufacturer whose most recently submitted mid-model year report contained an average fuel economy projection under § 537.7(b)(2) or, if no average fuel economy was projected under that section, under § 537.7(b)(1) , that was not less than the applicable average fuel economy standard in this chapter and who now projects an average fuel economy which is less than the applicable standard in this chapter shall file a supplementary report containing the information specified in paragraph (b)(1) of this section.(2) Except as provided in paragraph (d) of this section, each manufacturer that determines that its average fuel economy for the current model year as projected under § 537.7(b)(2) or, if no average fuel economy was projected under § 537.7(b)(2) , as projected under § 537.7(b)(1) , is less representative than the manufacturer previously reported it to be under § 537.7(b)(3) , this section, or both, shall file a supplementary report containing the information specified in paragraph (b)(2) of this section.(3) For model years through 2022, each manufacturer whose mid-model year report omits any of the information specified in § 537.7(b) or (c) shall file a supplementary report containing the information specified in paragraph (b)(3) of this section.(4) Starting model year 2023, each manufacturer whose mid-model year report omits any of the information shall resubmit the information with other information required in accordance with the NHTSA CAFE Projections Reporting Template (OMB Control No. 2127-0019, NHTSA Form 1474).(b)(1) The supplementary report required by paragraph (a)(1) of this section must contain: (i) Such revisions of and additions to the information previously submitted by the manufacturer under this part regarding the automobiles whose projected average fuel economy has decreased as specified in paragraph (a)(1) of this section as are necessary- (A) To reflect the change and its cause; and(B) To indicate a new projected average fuel economy based upon these additional measures.(ii) An explanation of the cause of the decrease in average fuel economy that led to the manufacturer's having to submit the supplementary report required by paragraph (a)(1) of this section.(2) The supplementary report required by paragraph (a)(2) of this section must contain: (i) A statement of the specific nature of and reason for the insufficiency in the representativeness of the projected average fuel economy;(ii) A statement of specific additional testing or derivation of fuel economy values by analytical methods believed by the manufacturer necessary to eliminate the insufficiency; and(iii) A description of any plans of the manufacturer to undertake that testing or derivation voluntarily and submit the resulting data to the Environmental Protection Agency under 40 CFR 600.509-12 .(3) The supplementary report required by paragraph (a)(3) of this section must contain: (i) All of the information omitted from the mid-model year report under § 537.6(c)(2) ; and(ii) Such revisions of and additions to the information submitted by the manufacturer in its mid-model year report regarding the automobiles produced during the current model year as are necessary to reflect the information provided under paragraph (b)(3)(i) of this section.(4) The supplementary report required by paragraph (a)(4) of this section must contain: (i) All information omitted from the mid-model year reports under § 537.6(c)(2) ; and(ii) Such revisions of and additions to the information submitted by the manufacturer in its pre-model or mid-model year reports regarding the automobiles produced during the current model year as are necessary to reflect the information provided under paragraph (b)(4)(i) of this section.(c)(1) Each report required by paragraph (a)(1), (2), (3), or (4) of this section must be submitted in accordance with § 537.5(c) not more than 45 days after the date on which the manufacturer determined, or could have determined with reasonable diligence, that the report was required.(d) A supplementary report is not required to be submitted by the manufacturer under paragraph (a)(1) or (2) of this section:(1) With respect to information submitted under this part before the most recent mid-model year report submitted by the manufacturer under this part; or(2) When the date specified in paragraph (c) of this section occurs after the day by which the pre-model year report for the model year immediately following the current model year must be submitted by the manufacturer under this part.(e) For model years 2008, 2009, and 2010, each manufacturer of light trucks, as that term is defined in § 523.5 of this chapter, shall submit a report, not later than 45 days following the end of the model year, indicating whether the manufacturer is opting to comply with § 533.5(f) or (g) of this chapter.