BMW keeps luxury sales crown as Audi, Mercedes catch up BERLIN (Reuters) - BMW (BMWG.DE) posted the smallest gain in December sales of Germany's top three premium-car brands as the battle with Audi and Mercedes-Benz DAIGM.UL for the luxury-sales crown is heating up. Deliveries at the luxury-sales champion rose 2.3 percent last month to 155,835 BMW brand cars, the carmaker said on Monday, dwarfed by an 18.4 percent surge at runner-up Audi (ADNC.O) to 130,700 autos, and a 11.2 percent gain at Mercedes to 139,180. With full-year sales up 7.5 percent to 1.65 million, the BMW brand retained a shrinking lead over its archrivals. BMW outsold Audi by about 80,000 cars in 2013, compared with 85,000 a year earlier, while the gap with Mercedes shrank from 220,000 in 2012 to 193,000 last year, company data showed. "BMW is showing signs of weakening while Mercedes enjoys very strong product momentum," Frankfurt-based Bankhaus Metzler analyst Juergen Pieper said. The big three are closing ranks. Audi and Mercedes, which dropped to third in 2011, have pledged to surpass BMW in sales by the end of the decade. To woo more customers, Audi is aiming to expand its lineup to 60 models from its current 49 by 2020, while Mercedes is planning to launch over 30 new models. Still, BMW said on Monday it aims to push deliveries to another record this year despite "difficult conditions" in many auto markets. Full-year group sales, also including the MINI brand, Rolls-Royce and BMW motorcycles, rose 6.4 percent to 1.96 million units, due to increased demand from China and the United States. Reporting by Andreas Cremer and Maria Sheahan; Editing by Christoph Steitz and Louise Heavens