Hi Martin,
Strangely enough I have a similar car. It is the same age 1999 but the 2.8 automatic engine. However we have done a lot more miles in her, 189000 last I looked. The side rubber strips peeled back a long time ago and our Audi approved garage glued them back on and they have been fantastic since. New Audi parts have not been available for years and the clips were not substantial even if new strips could be found.
You seem to have different wheel caps but I googled my new ones very recently. The originals were plastic on my car surprisingly and when one broke off I was able to get measurements and details so that I could find the correct new ones. They are a perfect match and when I had the wheels re alloyed they worked nicely.
Surrey Dents and Scratches in Chessington Industrial Estate and speak to Chris is my go to for bodywork. The touch up he has done has been phenomenal as far as colour matching on my Audi. But I suggest take the car to your nearest body shop should be able to do a good match on the colour it is now after 25yrs of weathering.
Hope that helps and best wishes with your project. It is a lovely thing to do for a friend and worth it for such a lovely car with such low mileage. regards Katrina
