[pwrdbym]

It's interesting to read opinions on this topic from 12 years ago.
I spend a lot of time tracking BMW values, part of my hobby is to "chase" what I believe are special examples in the hopes they'll be collectible (appreciate). The plus is I get to drive and enjoy all of them, (something I can't do with the money in my IRA). The definition of a high dollar collectible car is always going to be limited production, OEM condition, low miles, and no negative history. Rarer spec builds are also a criteria but usually one that makes an already collectible example more valuable.
Most models see a steep drop in value initially, like any other car, then it will level off. Average cars will stay at that level while the special cars will start to increase in value. We're seeing this now with the Z4M Coupe. The Z4M Roadster still has a flat line value. You can look to the Z3Ms for trends; obviously the Coupes are sought after, while the Roadster has only seen appreciation in the very nice examples.
I enjoy all the viewpoints on here, we have one hell of a fun hobby!