This is a genuine BMW locking button, part number 51 47 8 248 015. The number stamped on the part is 51478248015; BMW's catalog files it under the short number 8248015. You will find it on our Interior Body shelf, under Other Body equipment parts.
It fits the E46 sedan, coupe and convertible (320i, 323i, 325i, 328i and 330i, 1999–2006), with the M52, M54 or M56 engines — and the European-market versions.
BMW draws it on 4 diagrams, among them Lateral Trunk Floor Trim Panel (51_3257) and Lateral Trunk Floor Trim Panel (51_3743).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.