If you are willing to spend money then go for CIC + COMBOX retrofit. It is ultimate car infotainment + bluetooth system.
If budget is tight then go for aftermarket AV unit like Dension, or BMW module for AV.
535d LCI, Xenon Adaptive Headlights, ACC 2 (Stop and Go), Lane Departure Warning
Retrofits M5 heated/lumbar/memory and active backrest adjustment seats, rear heated and folding g seats, SAT Shifter, paddles (SA2TB), HUD, Rear blinds, Electric steering column, SA430 Folding and EC Mirrors, High Beam Assist, CIC, COMBOX Telematics, DVB-T TV, JBL MS-8, JL HD900/5 + HD600/4, Morel HO II, Morel Integra XO, JL 12W6v2 and Jehnert in Audio.