This photo taken at around 19:30 shows car dealers explaining to a large number of customers waiting to purchase cars at a car dealership in Shenzhen after the outlet was ordered to close. [Photo/CFP]

The topic, named "Shenzhen car restriction", reached 52 million viewers and ranked No 12 in the hottest topic list as of 15:30 pm on Tuesday.

Many users retwetted a statement made by a top municipal official to express their astonishment at the abrupt reversal of government's policy.

The government will solicit public opinion extensively before pushing forward car restriction and will not announce policies suddenly, said Wang Guobin, deputy director of Shenzhen police bureau, during an online interview in April.

A microblogger, using a name of Mr. Panming, also posted a photo of Xu Qin, mayor of Shenzhen, who had said Shenzhen will use economic methods to ease traffic congestion instead of restricting sales of new cars at a press conference at the beginning of the year.

Shenzhen had 3.14 million cars by Dec 20, 2014 and ranked first in density of car population in China, a news release by Shenzhen government revealed on Monday.

Shenzhen, in South China's Guangdong province, is the eighth city to adopt purchase restrictions following others like Shanghai and Beijing in waging a war against smog and traffic jams.