The German automaker delivered 588,300 vehicles worldwide from July through September, a 6.3% drop from the same period last year.
China was the main drag, with deliveries falling sharply amid intense price competition, cautious consumer spending and a broader slowdown in demand for premium vehicles.
Sales in Europe and the United States provided some support, but not enough to offset the decline in the world’s largest electric-vehicle market.
BMW has also faced production disruptions linked to a supplier-related braking-system issue, which affected deliveries of several models during the quarter.
The company is relying on new electric vehicles and updated versions of its core models to strengthen demand. However, competition from Chinese automakers and weaker economic conditions continue to pressure global luxury-car sales.
BMW’s results add to growing evidence that China’s auto market is becoming more difficult for international manufacturers, even as electric-vehicle adoption expands.