"For the first time in the company's history, over a million automobiles were sold by the end of the third quarter," BMW said in a statement.
Deliveries at the group's core BMW brand rose 2.2 percent to 113,979 units in September, while Mini sales fell 9.8 percent to 18,140 cars. In the first nine months through September, group vehicle sales rose 3.3 percent to 1,021,534 units.
BMW expects further growth in the coming months thanks to the relaunch of the 3 Series coupe and the new-look X3 mid-size offroader. Deliveries for both started on Sept. 23.
It also forecasts record sales for its Mini brand, as the next generation of BMW's highly successful retro-subcompact will hit dealerships on Nov. 18.
Chief Executive Norbert Reithofer, who took over from Helmut Panke at the beginning of September, had already told reporters at the Paris car show late last month that group vehicle sales would rise both in September and for the first nine months.
The group remains on track to reach its 2006 target of earning a record 4 billion euros before tax, including a gain of 375 million euros from the sale of shares in British turbine engine maker Rolls-Royce Plc.
Analysts expect BMW's new CEO, who was formerly head of production, to focus more heavily on expanding BMW's automotive margins as well as to push forward with a rapid expansion into new segments and new derivatives for existing models.
Last week, DaimlerChrysler's premium arm Mercedes Car Group posted a 1.5 percent decline in vehicle sales to 116,100 units in September as a double-digit drop in Smart sales dragged on results.
Volkswagen's premium brand Audi meanwhile had said unit sales rose 7.3 percent last month to 83,200 units helped by the all-new Q7 full-size offroader. It raised its forecast for full-year brand sales late last month.