Personally, I cannot stand driving a vehicle that is not loaded with options. Therefore , according to your choices, I would get the X5D. A similarly loaded 50i will put you damn near X5M Territory. It's sad to see base model luxury vehicles. Makes me think the person could barely afford it.

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2013 X5 Xdrive35i Premium
2013 F30 328i
2004 Mustang GT Very Modded...