March 24, 2005 notes from California Air Resources Board re "Corporate Fleet Average Weights (2002).xls":

Mr. Johnson,

Please find attached a spreadsheet with the data you requested.  Unfortunately, the spreadsheet from which the manufacturers' fleet average weights that are reflected in both the ISOR in Table 6.1-4 and the spreadsheet "For_costeffect_inventory, etc_082404" were derived was previously deleted.  However, the DMV data in that spreadsheet and "For_costeffect_inventory, etc_082404" in which the emission standards are calculated are identical.  I have reconstructed the derivation of the manufacturers' fleet average weights in the attached spreadsheet using the manufacturer data in "For_costeffect_inventory, etc_082404."  Note that there are two worksheets for GM, Ford, and DC due to slight errors in the original calculations.  One worksheet shows the derivation of the original manufacturer fleet average weight in Table 6.1-4, while the other worksheet shows the derivation of the corrected manufacturer fleet average weight.  The vehicles that were misclassified in the original derivation are noted in the worksheets.  A summary worksheet is also provided.  As a result of the correction to GM's fleet average weight, the maximum change in the emission standards is 0.31%.  Due to rounding, the standards in some cases increase by one gram per mile.  Given the uncertainty in the DMV data base, we do not believe that this requires changing the existing regulation.

A clarification on the structure of the emission categories - the PC/LDT1 category includes all passenger cars up to 6,000 lbs loaded vehicle weight (LDV) and light-duty trucks up to 3750 lbs LDV.
Should you need further clarification on how the fleet average weights were calculated, please contact me.

Regards,
Paul Hughes