I think one drive in the 5-series with AS and you'll say no to the option. It freaked me out while test driving a 4.8i taking a corner pretty quick (wanted to test the vehicle's agility). It's not very natural at all and takes getting used to because the variable is the speed and rate of turn, both of which are... well, variable. Try it regardless and see for yourself.

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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