When I first bought the 6 for my wife and I as a weekender, I had similar thoughts about the rarity, possible appreciation, etc. I kept it covered, stressed about every little ding, chip, putting too many miles on it and so forth; and then I started Autocrossing. I now care much less about all that and really just enjoy driving the heck out of it. I still hate dings, but have a great PDR guy now. I no longer think of it in terms of appreciating(would be great though of course)and am enjoying the car way more now. I'll drive it until the breather covers weep again; and then I'll clean and put some fresh RTV on and drive it some more. I probably didn't answer your question, just a few thoughts.