Rao Da, secretary-general of the China Passenger Car Association, said that environmental and traffic problems should not be attributed specifically to the increasing number of vehicles. "People's driving habits, as well as each city's road and infrastructure planning, should bear more responsibility," said Rao.

Statistics from CAAM show that in June, the combined market share of domestic automakers dipped 1.9 percentage points from May and 1.36 percentage points from a year earlier to 37.53 percent of the overall passenger vehicle market.

CAAM also said that in the first half, China's total automobile production and sales both passed the 10-million-unit barrier, with stable year-on-year growth of more than 12 percent, outstripping forecasts.

The positive increase was greatly driven by rapid growth in the passenger vehicle sector, said the association.

In the first half, 8.66 million passenger vehicles were delivered, up 13.8 percent from a year earlier, according to CAAM. The sport utility vehicle segment maintained its leadership in the market with year-on-year growth of more than 40 percent.

CAAM also said that in the first half, the commercial vehicle sector, including trucks and buses, reported positive year-on-year growth for the first time in the past two years with 2.12 million commercial vehicles sold, up 6.7 percent year-on-year.

However, Dong Yang, general-secretary of CAAM, said that although the first-half market performance far exceeded the association's forecast, "we retain our expectation of 7 percent annual growth for 2013, with overall sales of 20.8 million units, as there are still many uncertainties in the market for the second half".