WASHINGTON, D.C. — The U.S. Department of Commerce released retail sales figures today for the month of September. The report confirmed what other sales data sources reported earlier this month — that fewer selling says in September caused a sharp drop in auto sales.

According to the U.S. Census Bureau, total retail sales in September inched own 0.1 percent from August but increased 3.2 percent from the year-ago period. Excluding auto and parts sales, retail sales were up 0.4 percent from August and up 2.8 percent from September 2012.

Auto sales, including other types of motor vehicles, were down 2.4 percent from August but up 5.8 from the year-ago period. Including parts dealers, sales were down 2.2 percent on a month-over-month basis and up 5.1 percent from a year ago.

The drop, according to some automakers, was largely due to the sales calendar including Labor Day weekend activity into August figures. According to AutoData Corp., the calendar quirk sent the industry’s seasonally adjusted annual rate in September, which fell from 16.09 million in August to 15.28 million units, down to its lowest reading since this past April, when the SAAR fell to 15.19 million units.

The research firm, however, noted an 8.1 percent increase in retail deliveries in September vs. a year ago.