As a Grand Rapids Benz owner, I can suggest two possibilities for getting the car checked out, which he probably wants to do even though the mileage isn't great. Betten Imports, the local dealer, actually has a pretty decent service department
AFAIK; our experience with the Benz on a couple of things and on my daughter's VW has been fine. Prestige Imports is an indie that does most of the work on my Benz. They have bread-and-butter customers with Beemers, Volvos, Benzes etc. and sell a number of used MB, but they also are the area people to work on Ferraris, Rolls, etc etc; I've seen a lot of high-end vehicles there. Either should be able to do a proper PPI.