I have had good success in taking a MBZ to a good authorized dealer and paying for an "Inspection prior to purchase". Without a compression check it used to run about an hour, with about an hour more.
I have found the dealers will do this quite readily. They like creating a list with the potential to repair the car.
It is an impressive negotiating tool with the seller. Often the "list" from the experts not only gets the car to a good price, but also makes the buyer almost completely aware of what they need to do to the car.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)