[mermar]

I too have an e90 M3 and an X5. My new to me '16 X5 50i w/ DHP, B&O, HUD, MSport, Night Vision, etc... is the vehicle that I go to for DD, road trips, etc.. The M3 is an amazing drive and for me, a Formula 1 fan who longs for the NA engines, the S65 is something really very special.
But damn is the X5 50i effortless. In practical terms (I dont have access to a track so lets not go there) it is faster then my M3 in that it just breezes to 85-90 without the slightest attempt. With its hookup off the line it can really get going to 65 in a hurry. But I am not a teenager obsessed with printed 0-60 times. Rather I just gush over the visceral qualities of the e90M. The solid clunks of the DCT and the MPE noises - definitely feels like a retro car (already). They are obviously very different vehicles - but as a guy who likes to have a cooler of good beer under the cargo cover for after ride bench racing w friends while sitting on the super comfortable tailgate (mountain bike on the hitch rack) its sort of hard to not always grab the X5 keys.
Horses for courses... but I am likely to replace my X5 with whatever replaces the F15 50i - not interested in replacing the e90 with the F80. Probably just changing priorities.