In December sales plummeted 19.2 percent from a year earlier, the CPCA said.
The slumping market has hit China's manufacturing sector, which contracted last month for the first time in more than two years, according to official data.
Beijing's bruising trade war with Washington comes as it grapples with a slowing domestic economy -- growth is expected to have eased to around 6.5 percent in 2018, down from 6.9 percent in 2017.
The gloomy export picture has reinforced the need for Beijing to rely on its legion of consumers to grow its economy.
"I hope that's the case," he said.
Officials are taking steps to reignite consumer spending.
Still some officials have indicated car sales may have little room for growth.
"The period of rapid growth in production and sales of cars is over and low growth speed could become the norm in the automotive market," Xin Guobin, vice minister of industry and information technology said last year, according to China News.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)