Another question to ask about on a used car would be the tranny service. Mercedes specifies a 100k mile service cycle, using their $12/qt. "lifetime" fluid, however, I have seen picss of a car with only 50k miles and the tranny fluid was brown, and the pan covered in a sludgy mess. It probably would be a good idea to do a tranny service on these transmissions every 50k miles. a new tranny is several thousand dollars.