I believe they will be collectible someday, that's not why I own mine, but historically its the cars you dont expect to be collectible that do become so. Especially with the recent insurgence of powerful SUVs... theres historical precedence with the 4.8is, its the fastest of the first generation of "Fast SUVs" - it is to the X5M what the M535 was to the M5. And M535i's are quite collectible now.

I would also argue the X5M is already at enthusiast status now. I drove one the other day and have to say, I was quite enthusiastic about it! But seriously, there does seem to be a dedicated following to those vehicles.

Mind you, I'm under 30 so may have a different perspective than some of you guys. But I'm also a diehard BMW guy who has been in the Z3 world for 10+ years, so I've seen the zeitgeist in that community (coupes in particular) shift from that of a community on the fringe of the enthusiast world, asking "who would like these cars other than us?" to now asking "is my car worth 100K yet?"

I think whether a car becomes collectible largely rests on it's merits and it's place in the marketplace. The X5 4.8is is a truly phenomenal automobile. I've ran a BMW shop since so had the privilege of driving and working on a lot of BMWs. The 4.8is shares a spirit with the E39 M5 - it's right in that perfect sweet spot between new and old, analog and digital. New enough to be relevant, comfortable, and durable - old enough to be nice to drive, truly luxurious and encapsulating a spirit all it's own. And as I touched on earlier, it ushered in the era of super SUVs which we are still seeing grow and unfold.