I recently purchased a 2007 m5 with 28k miles on it, now 30k. Being a typical off lease car I was left with some deep scratches, car wash swirl marks, and acidic rain damage. I had my local detailer spend a day on it and was left unsatisfied and a majority of the damage still there. I came across "lord of the wheel" in the detailing section of the board and called him over to my workshop to re-detail my car. After careful inspection of my paint, he said the only way this paint would look brand new, if not better, would be a complete wet sand followed by a 7 stage paint recondition process. The process would take a few days, but I was willing to do it. Being a typical anal nut, I knew eventually the paint condition would bother me enough to sell it.
Being in the automotive service business, I have access to mechanics and a full workshop. We came up with a fun idea of doing an all out concours style detail with my car fully apart to make sure every single part was perfect. Naturally, everyone thought I was nuts but would help in the process. The entire project was an effort of 3 people with a total of 54 man hours spent. Turns out it wasn't that fun of an idea haha. I'm beyond satisfied with the results and can finally sleep well at night. A funny thing I noticed in the past few days is most people don't park next to it (I guess fearing scratching it, Imagine that in NY). Now all I have to do is find a clear film installer to make sure she stays this way.