I found the part number for the black cap that goes over the hole that allows you access to the torque converter bolts. The part is called "BMW Protection Cap" by BMW parts dealers. But ECS Tuning calls it Oil Pan Cap. I have been searching the net for this part for almost an entire year... here it is for your convenience.
https://www.ecstuning.com/b-genuine-bmw-parts/oil-pan-cap/11137543122/
https://www.ecstuning.com/b-genuine-bmw-parts/oil-pan-cap/11137543122/