I am getting approx 300 miles on a tank, in a mixed local/hwy driving (70% local / 30% hwy). It was much worse during the first 1000 miles, close to what has been reported in this thread.

It will get better, you need to let it break-in a bit and learn how to drive. I am watching instant MPG gauge, and see 20mpg on local driving if the road is flat.

On a recent trip upstate, I did 310 miles before a fill up, and could go for another 70 miles if not for the fear of not finding a gas station in the mountains on a weekend

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His : 2013 X5 3.5d Deep Sea Blue/Black/Aluminum with ALL packages, 20" 214"s, running boards, Adaptive Drive, Spare Tire, BMW Apps
On Order : 2016 X3 3.5 MSport Silver/Mocha with DHP, CW, Prem, Tech, DA, Lighting

Hers : 2015 328xi MSport Silver/Red

Prior:
2008 X5 4.8
2011 X5 3.5d
2010 335 xDrive
2013 335 xDrive