I believe that one is for import/export of data, such as: a) profiles and b) music that will be transferred (e.g. from CD/USB) to/from the vehicles hard disk.
Originally Posted by Doug in NC
I think the is another USB port in the glove box.
2013 x35i (Space Gray, MSport, CW/CWII, DHP, Premium, Premium Sound, Technology, BMW-Apps)
Retired:'09 C300 4Matic, '09 GTI, '06 750i, '05 C55, '04 R32, '03 M5, '02 GTI, 01 M5, '00 M-Coupe, '00 540i/6, '99 M3 Coupe, '98 M3 Coupe, '96 328i, ..., '86 4000CS Quattro, ... too many to list