Haven’t been on here in ages but thought this may be of use to other V8V owners of similar era to mine .
I had to pull the rear wheel liners to replace the marker light bulbs , got poking around in the drivers side fuel filler neck area

and found this . Removed it to investigate and it’s a filter , part of the emissions system ……..but look who it’s made by and the part numbers on it .
Goodness knows how much AM would want for it but it’s a $20 part from VW , takes two mins to change once you have the wheel well liner out .