BMW (the German motorcycle company) has not and will never build small (50cc) scooters. Not under the BMW label. According to van Hendrik (CEO).
There are big historic scooters (R10 with 200cc, gear box and Cardan shaft!), the C1 (125+200cc) with roof and safety crush zone and the actual C series (with 60hp not small either).
BMW ownes 100% of Husqvarna which have enough smaller engines (125-650cc).
BMW has a strategical partnership with Kymco. Kymco for small and medium, BMW for medium to big motorcycles.