For your wife??
Get her the X6 35i then and pocket a bunch of jing...I came from an 08 550i with 367 hp and am just fine with the 35i...And I've owned M3's etc..
Does the 50i have more hp and deeper growl? Heck yah....
But obviously value fits into some part of your buying decision and the 35i is plenty fast for a lot less $$$
Just a thought..
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Previous Rides: 535xi, M235xi, X3, E92 M3, E70 X5 35d, X6 50i, X6 35i, E60 550i, E46 M3 Cabriolet, E39 540i, E36 328i