When I picked mine up the dealer warned me to be careful as the 18s are easy to damage and not easy to repair because of the finish on them.
I had a slight disagreement with the smallest of kerbs, in my old car it would have been no problem but with the new GTI it was, it put a small mark on the rear left wheel. It is not really noticable so I am not too bothered about it. It is annoying though on a new car but I dont see much point in getting them repaired for one mark as I could then go out the next day and damage it or another one again. If it was really bad I would consider it otherwise I would spend my money on other things to do with the car, my next purchase is a Miltek, should be on there as soon as I get back and also possibly an air filter.