Well, he switched dealers. The "new" dealer has indicated there is a problem with a car. They have given him a loaner (an E320 4-matic! wow) and said they are going to keep the car for a few days to figure out the problem. They said they've seen one other car do the same thing, and are going to try the same solution.
When I get more info, I'll post...
1998 C230 "Black Betty"