Just took this shot to compare the Wix/Napa 46301/6301 to the OEM filter and they look to be about the same. Looks like the Mann might not be the best choice for a replacement for the BMW filter.
http://mrmaico.smugmug.com/Cars/BMW-.../IMG1430-L.jpg
Old pic from when I checked the fitment of the Napa Gold filter.
http://mrmaico.smugmug.com/Cars/BMW-.../IMG0962-L.jpg