One problem related to engine has been reported for the 2007 Mercedes Benz GL450. The most recently reported issues are listed below.
My 2007 mercedes-benz gl-450 with 36,900 miles suddenly lost power and was barely responsive while driving home yesterday (2/17/2010), and then the car required 3 or 4 attempts to shift into reverse as I was trying to back into my driveway. I drove the car to the mercedes dealership this morning. This problem first happened a few months ago (August 2009 at 34,500 miles) during highway driving with my family in the vehicle while we were out of town on a vacation trip. We had to repeatedly pull off the highway, turn the car off for awhile and then restart, to get the vehicle to have sufficient power to get home and to the mercedes dealership. At that time the mercedes dealership replaced a camshaft solenoid magnet. This problem is so dangerous that we have now lost confidence that we can safely take this vehicle on a vacation trip.