If the car is in prime condition. Almost no nicks or dings(God forbid; rust) in the body. The upholstery is like new, no cracks in the dashboard, very few cracks in the center console woodpiece, and maintenence records every 7500 miles BY THE AUTHORIZED MB DEALER! Then go for it. MB dealerships tend to replace parts that don't need changing often.
One owner cars are the best. Couple that with being serviced by the dealer since day one, and you have a car that has been overmaintained throughout its life.
Make sure the timing chain has been done(again) before purchasing, too.
1987 300SDL (324000)
1986 Porsche 951 (944 Turbo) (166000)
1978 Porsche 924 (99000)
1996 Nissan Pathfinder R50 (201000)