Have you considered putting him in an early 80's 300D diesel? They are hard to find in good condition.

In my opinion a 90 300E would be a good car for him. The engine is a single overhead cam type with a bullet proof bottom end. Does the car come with maintenance records? About the only issue that comes up about every 180k miles on that particular engine is that it starts using oil and requires a valve stem re-seal job. Does the a/c work? Does he care? The a/c can be a pricy fix unless you can do it yourself.

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Jim