The end of the year is traditionally the season for sales promotions in China's auto industry. But this winter, car dealers have scaled down their efforts, disappointing potential car buyers wishing to buy as they're concerned preferential policies may end.

At the Yayuncun car dealership, the largest in Beijing, many representatives say their sales surged since November. It's quite the contrast to previous months when very few consumers came to buy cars.

One car dealer of Yayuncun Car Dealership said "Many car buyers believe the city government may be considering curbing car purchases through license plate control, so they'd like to buy one before that happens."

There's also speculation that tax rebates and vehicle trade-in subsidies may be cancelled next year.

One consumer said "I'm worried that some preferential policies will be cancelled. I've also heard that it will cost more to get a license plate next year."

Other Chinese cities are also seeing a boom in auto sales this December. Some luxury brands are even short of storage in big cities.