This is a genuine BMW splash wall support, part number 51 45 8 172 862. The number stamped on the part is 51458172862; BMW's catalog files it under the short number 8172862. You will find it on our Interior Body shelf, under Covering, inner.
It fits the E36 sedan, coupe, convertible and touring (318i, 320i, 323i, 325i, 328i and M3, 1992–1999), with the M42, M43, M44, M50, M52 or S50 engines — and the European-market versions.
BMW draws it on the Dashboard Covering/Passenger's Airbag (51_2115) diagram. It weighs about 47 g (0.1 lb).
We have not had one on the shelf yet. Request it and we will tell you when one comes off a car.