In October, sales of commercial trucks and buses dropped 9.9 percent from a year earlier to 304,000 units, while sales of passenger vehicles -- which includes cars, SUVs, microvans and pickups -- rose 1.4 percent to 1.2 million units.

Overall, China's vehicle sales flattened after the government took steps to control inflation. In the third quarter, China's economy grew 9.1 percent, down from 9.7 percent in the first quarter.

Early this year, CAAM predicted that vehicle sales growth would range from 10 to 15 percent this year. Now, the association has reduced its annual forecast to 3 percent.

Demand for microvans and other entry-level passenger cars declined after the government ended tax incentives for small vehicles last December.

"There is a lot less potential for sales growth now, as deliveries were boosted by incentives in the last two years," said Klaus Paur, Shanghai-based managing director at Synovate Motoresearch. "We're now in an adjustment period and sales are slowing down. Chinese car manufacturers are the big losers as the segment is extremely price sensitive."

But luxury brands such as BMW, Mercedes and Audi continue to grow at a double-digit pace.

Thanks to stronger passenger vehicle sales growth early this year, China's overall vehicle sales in the first ten months increased 3.2 percent to 15.2 million units.

Passenger vehicle sales in the first ten months increased 5.9 percent to 11.8 million units, while commercial vehicle sales dropped 5.3 percent to 3.4 million units.