TrueCar.com forecasts that the US light vehicle market in August will be up 17% at 1.255m units.

The company also says that it estimates the August Seasonally Adjusted Annualised Rate (SAAR) at 14.2m, up from 12.1m in August 2011 and also up from 14.1m in July 2012.

"While the overall economy remains at a stand-still, auto sales continue to be strong as August marks the third straight month of SAAR over 14 million," said Jesse Toprak, Vice President of Market Intelligence for TrueCar.com. "Domestics continue to lose market share as the strength of the Japanese recovery continues. Volkswagen is quietly becoming a serious player whose growth can't be ignored."

"Incentive spending in August is around the lowest level we have seen this year and has decreased for the fourth consecutive month," said Kristen Andersson, Senior Analyst at TrueCar.com. "Automakers continue to optimise incentives and spend less dollars-wise despite the big push this month to sell down inventory on older models."