
BMW posted a 6% gain in September, delivering to 27,467 cars and sport utility vehicles.
The 3 Series sedan was up 19% and the X5 SUV more than doubled sales from a year ago.
Mercedes deliveries rose 4.8% to 27,433, paced by deliveries of its GLC and GLE SUVs, which jumped 13% and 28%, respectively.
BMW has a lead of more than 8,200 vehicles over Mercedes year-to-date.
But the latter is regaining some momentum after supplier bottlenecks at its assembly plant in Tuscaloosa, Alabama, left dealers with inventory shortages earlier this year.
Toyota Motor Lexus, which outsold the German luxury leaders in both July and August, reported a 17% plunge in US deliveries last month.
Sales of the ES, the brand’s top sedan, tumbled 36%, while the RX SUV, its most popular light truck, fell 12%.
Volkswagen’s Audi division also slumped in September, with a 17% slide.
Deliveries of its best-selling SUV, the Q5, fell 41%.