One problem related to diesel engine has been reported for the 2007 Mercedes Benz GL450. The most recently reported issues are listed below.
On three separate occasions the 'charge air hose' connecting to the turbo intercooler system on my 2007 mercedes gl320cdi has failed. The hose has been replaced four times total. According to internet message boards there are numerous failures that mb has failed to fix including mine. On all occasions of the incident my entire family has been in the vehicle. While under acceleration the hose fails and forward speed is lost. On two occasions I have been on the interstate and driving on the incline of a hill where other vehicles were behind me. It is not safe.