China has overtaken the U.S. to become the world's largest auto market. But growth in Chinese auto sales slowed in July.

Passenger car sales slowed to an 11 percent growth rate, down from June's 15.8 percent rate, according to China Association of Automobile Manufacturers, quoted by the AP.

Meanwhile, total vehicle sales climbed 8 percent, down from 10 percent in June.

Last night, China's massive economic data dump showed that retail sales slowed to 13.1 percent year-over-year, and a sub-index showed that auto retail sales growth by value fell to 4.7 percent in July, from 6.2 percent in June.

This will definitely be worrisome for international car manufacturers that have been looking to China too boost auto sales as their local markets slow.

In fact, the focus of the auto industry has been shifting to China, after auto sales jumped in 2009 after Beijing cut taxes and offered subsidies in the wake of the 2009 financial crisis. IHS Global Insight had projected that annual auto sales in China will grow by 74 percent to over 30.6 million a year by 2020.

Despite the growth prospects, automakers will be concerned with the recent slowdown in China, the investment in subways and railways, and curbs on auto sales in cities like Beijing, Shanghai, Guangzhou and Guiyang.