German automaker BMW sold more than 20,000 units of its 5 Series here during the first 10 months of this year, maintaining its lead in the premium imported car market, it said on Thursday. Sales of the sedan reached 21,552 units through October, slightly up from 21,364 units in the same period last year, making it the best-selling import in its segment in South Korea. The automaker attributed the strong performance to the sedan's wide range of optio