The option was called Anthracite Birch effect trim and is like rocking hourse ****. I have only ever seen 2 M5's in the UK with it.
Although early 96-98 528 sports had a similar gloss black trim as an option, though not wood effect, looks great.
I was very lucky to spot a 528 being broken on ebay with the trim and picked it up for £100 delivered (approx 170USD) from the breaker

it even had the panel with the tyre monitor button in
Maybe an option...
All the best
-Steve