Previous owner probably wore jewelry and car was most likely parked in sun?...........that'll do it. Mine's garaged at home and work and I wear no jewelry so mine looks all fresh and minty like the one in the pic above. Contact scratchnsniff (member on here that is one man protg parts house) for a fresher wheel.
What piece are referring to? The pictures above are exactly what my 03 P5 looks like.