China, currently the world's largest auto market, is also GM's biggest by volume. VW is the leading brand in China - also its largest market.

Margins on auto sales may not be what they are in the United States or Europe, but China is now the world's largest auto market and GM's biggest market by volume too.

GM posted record sales in China for the first half of 2010, with a 48.5 percent increase in sales over the same period last year. GM sold 1,209,138 units in the country for the first six months of 2010, vehicles it builds in concert with its Chinese partners, compared to unit sales of 1,069,577 in the United States.

GM sales were buoyed by the popularity of models such as the Cadillac SRX, Chevrolet Cruze and new Chevrolet Sail. GM's Buick is also one of the fastest-growing brands in China.

GM now ranks second in China, behind Volkswagen, in unit sales. China is also now VW's largest market. Last year, China overtook the United States as the world's largest vehicle market, albeit, after the U.S. experienced a precipitous drop in car sales due to the financial crisis of 2008-2009.

For the first five months of this year, vehicles sales in China were 7.1 million compared to 4.6 million in the U.S.