GM sales drop 11 percent
Retail sales, excluding fleet sales, for all eight brands were down 29 percent.
But the month was not a strong one, with GM's four viable brands reporting a 7 percent drop-off from July, suggesting the road to recovery continues to be a long and sputtering one.
The fastest growing brand is Buick, which is up 61 percent for the year and 66 percent in August.
Cadillac saw an 83 percent increase in August and is pacing 50 percent ahead of a year ago.
Chevrolet took the biggest hit in sales last month with a 22 percent decline from August 2009 but is up 19 percent year-to-date. The brand is counting on the launch of the Volt electric vehicle in November and the Cruze compact car this month to boost brand sales.
GMC saw a 12 percent increase for the month and is up 26 percent for the year.