The W116 is described as notorious for rust in certain spots, with the windshield pinch weld a near-universal issue costing around $3,000 to repair correctly plus a $125 gasket. Bumper rust originates inside the rubber-encased metal strip where water gets trapped, eventually bulging and splitting the rubber; buyers are urged to inspect the undercarriage carefully.
Rust: windshield pinch weld and bumper corrosion
Mercedes-Benz 450SEL 6.9 · cosmetic