The underlying data is currently provided by Ward's Automotive Group.Further information on the use of auto unit sales in the preparation of PCE estimates can be found in U.S. Department of Commerce, Bureau of Economic Analysis, Personal Consumption Expenditures, Methodology Paper Series MP-6 (1990). SAARTOTL Index: the seasonlly adjusted annual sales of total light vehicles sold in U.S., in millions.Total sales are broken down by cars and light trucks that are manufactured in U.S., Mexico and Canada (Domestic), and those manufactured elsewhere (Imported). These figures in SAAR index are calculated as follows: the monthly sales divided by the SAAR factors (The Seasonally Adjusted Annualized Selling Rate) provided by the Commerce Dept. The SAAR factors adjust for seasonal changes in sales and annualize the figures, making comparisons of the monthly data moremeaningful, Please see ATSL <GO> for all auto sales statistics. Data prior to 1991 is taken directly from the Commerce Dept., Data revision dues to seasonal factor revisions by Commerce Dept. on 9/1/04 - revision from 1/2000 - 7/2004, on 2/18/04 - revisions back to 1993.On 7/31/10, revision from 1/31/2002 to 6/30/2010.