Well, I have A LOT of experience with this. My almost 1 year old (at the time) X5M developed the same issue. I was driving one day, engine malfunction light came on and had reduced power. Pulled over, stopped the car and let her sit. Restarted and then drove about 10-15 minutes and same thing. Kept happening the rest of the day and car finally went to the dealer.

30+ days later the dealer had replaced both turbos and "adjusted" the turbo software. Drove the 2 hours to pick up the car and about 40 miles away, it started again. Same sputtering and low power feel. Back on a flat bed the next day. Another 40+ days, head engineers coming in from Germany and South Carolina. No idea. Flashed the car. "Could not reproduce symptom." Would always occur for me going up hill, in M mode, and down shift. However, dealer couldn't get it. Came back. Informed BMW service that I would like to discuss a replacement. They said wait and see what happens. Literally after leaving the office home it occurs again. Called BMWNA (with whom I had called after the second tow in to begin a ticket) and told them that I wanted a replacement. I also called BMW HQ in NJ. Discussed it their as well.

Kept the car for another 1 week waiting to hear from BMWNA. On way out of a gas station car refuses to shift forward from 2-3. This as a semi comes barreling at me. I called BMWNA and told them where they could find the vehicle and that I was not driving it. At this point, it was over 120 days from start. I was given the run around that I had bought the vehicle in one state, lived in another but serviced in a third (it was the nearest BMW dealer). The quote was "we are sure how the lemon law would work". I replied with "you have dealerships in every state, lawyers who are well versed in the business of keeping BMW operating, and you tell me that you don't know how the lemon law would apply?". I finally had to have my attorney send a letter to the dealer.

Suddenly I got a call back saying what would you like to order? I had them take my car back and switched to a 2011 Cayenne Turbo. No issues for six months and upgraded to 2012 with custom order. I haven't looked back despite my enormous respect for the X5M/X6M. Thought about going back once, but seems there are more of these occuring.

What was the final result/problem, etc? BMW had no idea. Could not figure out the issue. The codes coming from the car where consistently show turbo faults. No matter how much they adjusted the turbos, replaced the turbos, etc, the problem was not fixed. So, I had to walk away.

I sincerely hope you have better luck. I hope yours is an easy fix and the problem is identified and remedied. Please keep us up to date.

J