Thank you, Wizard, for the useful reply. I will keep your recommendations for future reference. I hope the discourse of this message thread helps someone else who is as ignorant as I am (or was) about what Starmark Certified actually means. I think it means: "We'll sell you a vehicle with no better assurance of quality or condition than any other used vehicle on the street, but we will charge you more for the vehicle and make you think you're getting warranty coverage as a bonus."

One last observation: According to the Mercedes Customer Relations Liaison and confirmed by others on this forum, frame damage would exclude a used Mercedes from being Starmark certified. That said, there is in practice no modern Mercedes passenger car that could possibly be excluded from Starmark certification due to frame damage, because modern Mercedes passenger cars use unibody construction*. They do not have a frame^. With unibody construction, any significant damage to any part of the body, whether sheet metal or stress bearing, necessarily and by definition affects the integrity of the body. A frame is not involved.
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*unibody construction - "a manufacturing process where sheet metal body parts are combined with stress-bearing elements to form the body and chassis as a single piece, as opposed to attaching body parts to a frame"
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^body-on-frame construction - "a type of automobile construction in which the body structure is attached to a separate frame"

 

You should just take the bus.