I was very skeptical about this whole 'claying' the paint. I've heard of other people talking about it in the recent past & had the deer in the headlights look. Never heard of a real detailer using clay on a car. Thought it was one of those late nite info-mercial products. Then I read about it on proper auto care's website. Turns out, that it is actually a fairly recent discovery in cleaning paint. So, I picked one up for my 4 year old 4-Runner (Black). All it took was a pass on a 2x2 portion of the hood. What came off the hood looked like grease! I am now a firm believer in claying a car.
You shouldn't have any fears of using clay, as it is virtually idiot proof(as long as you follow the directions).
I have yet to set aside enough time to do my 330i. Still need to get a deal of Menzerna for some minor swirl removal.
As a side note, I used Pinnacle Souveran paste wax on my Imola Red 330i,...Oh MAN! I spell it M-A-N. That's everything man!