I agree with Jim, the guy should get a Honda.
Again, here is the link:
http://www.complaints.com/directory/2004/february/12/6.htm
We don't have the specifics, such as model, year, and mileage, but some cars (any car) reach a point where they are in constant need of maintenance and repair.... more so with high mileage late model Benzes that have evolved into complicated pieces of machinery with considerably more parts than earlier Benzes.
I'm not a professional tech. I limit my work to family and sometimes friends who beg hard enough. But all too often I finish repair on one issue, and find that something completely unrelated has crapped out on the car while it has been in my garage. Family is understanding. This would be a nightmare situation if I was dealing with the public, having to explain that it wasn't my fault.... just bad timing on the car's part. That's why I have no aspirations in owning any kind of auto repair business. I just don't see how you guys can handle fickle cars and wary customers.