I did a bit of work on the X3, I cleaned the MAF, checked the disa which was sticking, I freed it up and then took the car for a decent drive. The improvement was nearly 1.5l per 100kms around town. Part of the issue was that the trans needed a service and was slow to shift up, and that combined with my daughter erratic driving style contributed to the average economy. I also performed and oil change but I cant see how that would have influenced economy. I also had a faulty coil so I replaced it a good second hand one I had. The car was certainly a bit smoother. Its got to go, My wife has her eye on a e92 Wagon.