The corrugated line is part of the evap control system. Not exactly vacuum, but the DMTL pump pressurizes the system to check for leaks.
It doesn't look right on this diagram, but this is the part number:13907530976
http://www.realoem.com/bmw/enUS/show...34#13907530976
Looks like this:
https://www.ecstuning.com/b-genuine-...e/13907530976/