In my driving, I get about 16 mpg on the second tank with city short distance driving if I reset and accumulate for a few days. After driving around freeway for a while, it inches back to respectful 19.7 mpg for the second tank. The first tank did not count. It was mostly freeway driving without aide of cruise control. I still get respectful 23.x mpg.
What I noticed is that X5 needs a light foot to switch gear at around 1750 rpm. If you can get to that point, then it get boosted quite a bit. So what I do is ease off throttle near that and my mpg shoots up. I guess it is my version of the eco mode. Also, the gear shifting point is different when you start engine at cold. Cold temperature tends to get the transmission switches at closer to 3000 rpm.
What is the message? Early morning MPG sucks. Drive lightly and things will come back up to normal.
2012 BMW X5 Vermilion Red Xdrive35d with Premium Package, 3rd Row Seats, and Adaptive Drive