I personally know a Cadillac mechanic ( they charge the same rates as M-B ), that spent an entire WEEK finding a problem on an Escalade.
Buy ANY " high - end " i.e. expensive vehicle, with all the bells & whistles and I wish you the best of luck.
Maybe not so much the original owner ( Lesee ), but the poor schmuck that buys the vehicle when it is 4 or 5 years old.