as an owner of both (07 X5 and 08 MDX---and recently traded toward 2011 X5 and 2011 MDX) I can tell you that the X5 is superior in many ways. Build quality, ride, comfort all areas where the X5 excels. But this comes at a price, and comparable X5 is much more expensive.

When traveling, we always drive my X5, far more comfortable ride. The build quality is noticeably better in the X5 as well. One other point, despite the hate for the idrive, I find the idrive far superior to the MDX cluster f**k of menus and knobs. The MDX is not nearly as attractive as the X5 either.

I have been driving both for nearly 5 years now and two MY changes.

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2013 X5 35i M Sport