With just under 3,000 miles I am now getting 13-13.5mpg in city with some mixed tollway driving. If I drive pretty aggresively I will get 12.8-13 but have seen close to 18 on longer hwy commutes. I think sticker of 13/18 city/hwy is pretty accurate. I may get slightly more that 13 one the car is broken in even more. I have noticed mpg getting a little better because I was getting 11.6-11.8 mpg until I hit over 2,000 miles.

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2009 BMW X6 50i