Simple answer is this will not be easy. As you yourself say "where would they go"?

When i bought a stand alone Sat Nav about 10 years ago there were some available that had a bluetooth function, they may still be available form TomTom, Garmin etc. I appreciate they are not as pretty as a built in one but they cost £100's at best, a built in one would cost way more.

We have since had one new car with built in Satnav (free model upspec by the delear) and when delivered the maps were 2 years out of date (probably older in truth - that was the date of the saftware version). Ti get updates was stupidly expensive, think it was just over £100 and the dealer said the maps would still be out of date. The bits you acquired out of a 10 year old BMW would be similarly out of date and the bluetooth bits might not even work with a modern phone.

Both our car use Android Auto and with that we can use the Maps App on the phone. We actually use Waze now because it does traffic, roadworks and speed cameras all for free (and the maps are regularly updated free as well). No idea if you could get a suitable head unit for your car but might we worth asking on the BMW Forum.

Will never have a built in unit again (unless its standard of course).

Edited by skidpan on 26/09/2018 at 11:22

What is your budget?

For £60-£100 you can get brand new Garmin/TT Satnav with Blutooth +free map updates (until they discontinue for that model). Solves a problem but leaves others unanswered.

Loads of money

I am sure somewhere there is a scrappy will have built in kit from 2009 & another scrappy somewhere has the housing to fit a 520 from 2009 & then you need an car electrician who knows his way around a 10 yr old BMW at a time when car electrics become problematic.