That doesn't sound right, theres no reason any car built after the early 90's should rust. I live in salty New England and have never seen a W210 with rust or peeling paint, and I see some neglacted W210's. Maybe a bad batch of undercoating got threw? The paint peeling would be owner abuse. Even a Neon given a coat of wax once or twice won't shed its paint that fast.

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2006 CL500
2009 C300 4matic
1969 280SE
2023 Ram 1500
2007 Tiara 3200