I wouldn’t not buy a w210 because of the rust by any means. That’s how I’ve gotten quite a few of my cars dirt cheap. The arch repair panels for the quarters were $30 a piece and the rockers (common rust point) were $75 a piece for a whole outer rocker skin. Fenders easily sourced etc. I’ve never done a perch, but that’s easy too. The undercarriages really don’t rust that much besides the spring perches. I usually just don’t drive a car when it’s super rusty because it’s embarrassing to be driving a Benz covered in rust. It’s supposed to be clean and nice.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k