In case anyone is wondering, I drove my X6 from San Diego to Malibu today for a car meet. Through all the hills and such with the roundtrip ride, I averaged 21.5 MPG. I only have 800 miles on the odometer. When the engine is fully broken in I hope it will be even better MPG. At 21.5 MPG, I can go about 480 miles on a tank.
Not bad for a 5,000 lb truck.