Potential car buyers in Shenzhen, Guangdong province, might have to think twice before purchasing new vehicles, as the auction price for a car license plate has rocketed to a record high.

In December, the average price reached 95,103 yuan ($14,525), the highest since the city began requiring prospective buyers to acquire car plates by lottery or auction in late 2014.

The auction price has increased sharply for six consecutive months, according to the city's transport commission.

The move to introduce auctions was aimed at easing the worsening traffic congestion and promoting environmentally friendly transportation in Shenzhen.

More than 260,000 people participated in the auction in October, almost double that of August, according to the city's traffic authorities.

"In recent years, the auction price for a single car license plate was less than 50,000 yuan, which, in my view, is acceptable," said Zhou Yuanzhi, who works for an electronic device company in the city's Bao'an district. "Now I have to think twice before deciding to buy a car."

Shenzhen, which has a permanent population of about 11.9 million people, has more than 3.18 million vehicles, according to the transport authorities.

"It might be the most expensive car license plate, given that one in nearby Guangzhou is about 20,000 yuan," Zhou said.

Zhou lives in the suburban district of Longhua and has to spend about an hour on the bus to get to work.

"Public transportation, including buses and subways, needs to be upgraded. Otherwise, there will be more people willing to buy new cars, which will in turn push up the auction price for car license plates," he said.

According to the plan to limit car purchases, 100,000 new vehicle plates will be allocated annually for the city, with half of the plates being distributed through lottery and the other half by auction.

Feng Shengping, chief researcher with the Guangdong Academy of Social Sciences, attributed the high auction price to the recent ban on vehicles without local license plates from Shenzhen roads during rush hours.

"The local government is determined to promote green transportation and tackle the problem of traffic congestion by introducing such restrictions," Feng said.