you may want to buy a mat for the baby carrier so the weight doesn't mark the bottom of your rear seats. Any can be had for under $20 at Babies R Us. I think I went with Eddie Bauer ones and they're pretty thick while still foldable (and washable).

For the trunk, I would recommend the fitted "luggage mats" that may run just under $100. Great peace-of-mind knowing you can toss anything in there without scratching the track or ripping the carpeting. It's also good at protecting from spills.

BTW, you didn't list comfort seats... which seats are those? It appears the headrest side button is different then ours now.

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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