BMW AG said on Friday it had won key approval from Beijing to start building cars in mainland China from the second half of 2003, a major step in its bid to double Asian sales over the next five years, Reuters reported. Confirming an earlier Reuters report, BMW said Beijing had approved a feasibility study on a planned deal with Brilliance China Automotive Holdings to build up to 30,000 BMW 3 and 5-series cars per year in the northeastern Chinese province of Liaoning.