3) It has been discussed many times but people have also said it's less glare if it's down low on the center console. Some have said it leads to motion sickness though. Between the two choices, I'd rather have it in the headrests as it doesn't take away room from the armrests (and they can open too). Will need window shades.

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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