Dongfeng Peugeot Citroen Automobile, a 50-50 joint venture between PSA Group and Dongfeng Motor Group, lost nearly 3.7 billion yuan ($552 million) in 2018 on plunging sales.
That was about eight times the loss of 465 million yuan the partnership incurred in 2017, according to Dongfeng, a Hong Kong-listed, state-owned Chinese automaker.
After hitting a high of 704,000 vehicle sales in 2015, the JV's annual deliveries have slumped for the past three years. In 2018, sales plunged 33 percent to around 253,000.
As a result, 2018 revenue fell 31 percent to 28.3 billion yuan.
The JV, headquartered in the central China city of Wuhan, can produce up to 840,000 vehicles annually for the Peugeot and Citroen brands at full capacity.
This year did not begin well for the venture as sales tumbled 63 percent in January to around 12,300, according to the China Passenger Car Alliance, a Shanghai consultancy.
PSA also operates a joint venture with Changan Automobile, which builds and markets DS cars. But this JV has fared no better than Dongfeng Peugeot Citroen.
With annual production capacity of 200,000 vehicles, Changan PSA sold fewer than 3,900 vehicles last year, according to China Passenger Car Alliance.