Dongfeng Motor Group Co, China's third-largest automaker, said on Friday its passenger car sales fell 6.2 pct in August from a year earlier.
It sold 50,989 cars last month, down from 54,354 units a year earlier, it said.
Dongfeng Motor gave no explanation for the sudden drop in sales after years of double-digit growth.
Analysts have said the two week-long Beijing Olympics, which ended on Aug. 24, and a slowing economy kept buyers away from showrooms.
The company's total vehicle sales fell 11.2 percent in August to 69,767 units, versus 78,539 a year earlier.