General Motors experienced a 10-percent sales increase last month over August of 2011. The car giant sold 240,520 units across its four marques, with Chevrolet, Cadillac, Buick, and GMC all reporting year-over-year increases.

Retail sales were up 11 percent, while fleet sales were up 6 percent.

Chevrolet's sales were 11.3 percent higher than in August of 2011, with 169,978 units sold. Year-to-date sales stand 5.3 percent higher than in the same period last year, with 1,270,582 Chevrolets sold so far this year.

GM attributes Chevrolet's August sales bump to the national advertising campaign broadcast during the Olympic Games. The Spark, Cruze, Sonic, and Volt each experienced a best-ever sales month, while sales of the Equinox were 22 percent higher than in August of 2011.

"The single message Chevrolet communicated this summer was 'confidence' and it rang true with customers when they saw how our product lineup is being transformed," Kurt McNeil, vice president of US sales operations, said in a statement. "All four of our brands are building momentum behind new products so we're very well positioned as the economy continues to slowly improve."

Cadillac sales improved 11.3 percent year-over-year, with much of the increase due to sales of the SRX crossover, Escalade SUV, and XTS large sedan. The luxury marque sold 14,704 vehicles in August. Year-to-date sales, however, have decreased 9.5 percent from their 2011 levels, with a total 90,933 sold so far this year.

Buick's 12-percent sales increase was driven largely by the Verano, which has increased in sales for each of the nine months it has been on the market. Sales for the marque were the best they had been since September 2007. Like Cadillac, however, Buick has experienced a decrease in year-to-date sales. So far this year, 108,892 Buicks have been sold, a 3.1-percent drop from last year.

GMC sales were up 4 percent, in spite of a 35-percent drop in (the less profitable) fleet sales. The Acadia's sales were up 26 percent, while the Terrain's sales were up 16 percent.

New products creating buzz are the 2013 Chevrolet Malibu and Cadillac ATS. Throughout 2012 and 2013, 70 percent of GM models will have been redesigned.

While two brands have seen year-to-date sales decreases, GMC as a whole has experienced a 3.7-percent increase in sales, with 1,757,470 vehicles sold so far this year.

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