I've been on this forum since the E70s came out (and really the only reason) and I'd have to say you should be wary of '07s first-model-year issues moreso than any 3.0-specific issues. I haven't really seen consistent issues with the 3.0 engine mentioned on this board. I've had a couple battery drain messages in 3 years, but recently I broke my foot and couldn't drive it for 3 weeks straight and it started right up, even in the cold weather. When I did get the warning almost 2 years ago, I had been driving it consistently. It really is a crapshoot as far as that goes.

Common first-model-year issues include creaking/rattling, and some interior peeling on steering wheel & light switch (my 08 had it too). If I were looking at an 07, I would try and drive it as much as possible first.

As for the aftermarket warranty, at the prices they charge, I'll take my chances considering I don't put all that many miles on it and it's a set amount for just 2 years. I suppose it's worthwhile if you really put the vehicle through its paces daily. Was your E53 relatively trouble-free? I know its got less gadgets, just wondering.

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'08 X5 3.0si - Alpine White / Saddle Brown interior
Specs: Sport Pkg, Premium Pkg, Tech Pkg, Comfort Access, Aero Kit, Style 433 staggered 20s on Conti DWS
Mods: Carbon 35 tint, LED angel eyes, GP Thunder 7500k fogs, H&R 20mm/25mm spacers, clear reflectors, gunsmoke-tinted taillights
Coded: Digital speedo, windows/sunroof/tailgate close via keyfob

X5 pics at Flickr