I recently bought a CPO 2007 X5 4.8i. I have had several problem, but the dealer has been pretty good about fixing them all, including reprogramming the transmission! However, one problem they are claiming is "Normal" is that the Cruise Control surges in speed ranges between 40mph and 55mph. That is if I ask for 55 mph, and there is even the slightest hill, the car begins surging back and forth rather noticably trying to maintain the speed. MPG fluxuates very clearly, and the tach does fluxuate back and forth, but the frequency is so rapid it is difficult to see. I was told by the dealer that it was the Torque Converter locking in and out. If I move the transmission shifter to "Manual" the problem stops. Does anyone with a 2007 X5 4.8 have a similar problem, or does yours run smoothly. I would appreciate any input.