The Chrysler Group, aided by a 21 percent gain in car deliveries and an 18 percent increase in Ram brand volume, posted a 14 percent increase in August sales.

General Motors said Olympics advertising and a Chevrolet promotion pushed its August sales up 10 percent. GM's four brands--led by a 12 percent gain at Buick--all posted increases last month.

Strong demand for utility vehicles helped Ford Motor Co. report a 13 percent increase in sales last month, with retail volume up 19 percent over August 2011. Sales rose 13 percent at the Ford division and 2 percent at Lincoln.

Ford said deliveries of utility vehicles jumped 28 percent, while car sales climbed 7 percent and truck volume rose 6 percent. The company said it also plans to boost fourth-quarter North American output by 7 percent--or 50,000 vehicles–to 725,000 over 2011.

Volkswagen AG said U.S. sales at the VW brand surged 63 percent to 41,011, its 24 consecutive monthly gain.

It was Chrysler's 29th consecutive monthly increase in U.S. sales, though the gains have slowed over the last two months from their torrid pace early this year.

The automaker continues to benefit from new or refreshed models, notably a stronger passenger car lineup, as well as generous incentives, fleet shipments and easing credit terms.

Chrysler said volume rose 25 percent at the Chrysler brand, 34 percent at Fiat, 13 percent at Dodge and 5 percent at Jeep.