A recent development for my Z4 has been treating the paint. After testing a 540 fender (that I painted with acrylic) at Meguiar's I decided to treat the paint on the Z4 using what I learned from that night. The acrylic clearcoat is much more resilient than I expected.
The process I used was red pad with Ultimate Compound, usually two (heavy) applications, followed by black pad with #7 glaze, followed by Tech Wax applied and removed by hand with a rough microfiber applicator (closer to terrycloth) and microfiber buffing cloth.
The interesting thing about this paint is that it requires a long tooth on any towel to really get into all the texture of the paint. Conversely, the paint is so elastic that it's very hard to scratch. So this is a rare circumstance in which a terrycloth rag is better than microfiber.
Here are a couple before/after pic sets that show the effect of this work. Note that the goal is not to eliminate the brush marks, but to bring a more even gloss to the paint.
Before:
After:
The trunk half the blue area has been treated, the roof's half has not:
Before:
After:
Before:
After:
Overall the paint colors are more vivid and the finish is more glass-like. To describe using Home Depot's interior finish chart I would say it's gone from a 3 (satin) to a solid 4 (semi gloss).