Yes, I thought it might hit 20 mpg average after break in (given my highway ratio) and that made it somehow easier to mentally justify. I have tried to draw the line in the sand at 20 mpg which is why I am waiting for the X5 diesel.

I haven't seen any official mpg figures from BMW on US spec. The mileage you mention sounds a little high, do you need to adjust for the Imperial gallon?