61 13... Circular connector, 20-pin, system D2.5
WARNING: This page is about a different car, the 2016 BMW Z4, 2015 BMW Z4, and 2014 BMW Z4. However, it is still accessible from the selected car via links, so may be relevant.
Special tools required:
Carefully press back retaining tabs (1) of internal connector (2).
Turn internal connector (2) until retaining lugs (1) snap into release groove (3).
With special tool 61 0 303 press down retaining hook (4) of corresponding contact and pull out cable.