40 CFR § 1037.735 - Recordkeeping.
(a) You must organize and maintain your records as described in this section.
(b) Keep the records required by this section for at least eight years after the due date for the end-of-year report. You may not use emission credits for any vehicles if you do not keep all the records required under this section. You must therefore keep these records to continue to bank valid credits.
(c) Keep a copy of the reports we require in §§ 1037.725 and 1037.730.
(d) Keep records of the vehicle identification number for each vehicle you produce. You may identify these numbers as a range. If you change the FEL after the start of production, identify the date you started using each FEL and the range of vehicle identification numbers associated with each FEL. You must also identify the purchaser and destination for each vehicle you produce to the extent this information is available.
(e) We may require you to keep additional records or to send us relevant information not required by this section in accordance with the Clean Air Act.