NHTSA Complaint #11663816 — 2015 MERCEDES-BENZ C300

Rear-subframe corrosion at the lower-control-arm mounts has progressed to the point where both arms have play and produce loud metallic bangs while braking or turning at low speed. Two independent shops lifted the car, documented flaking rust around the bushing sleeves, and advised the subframe is structurally compromised and could let a control arm detach under load. The corroded subframe remains installed and can be inspected on request. Safety risk: a detached rear control arm would cause sudden, unpredictable steering and loss of control. The vehicle already pulls right under braking, and feels very unstable in curves Problem has been reproduced and photographed by two independent repair facilities. No manufacturer representative has inspected the vehicle so far. Additional component failures possibly linked to the same progressive chassis stress: premature wear of both front CV axles; timing-chain stretch with worn guides; slack oil-pump chain; upper & lower oil-pan gasket leaks; water-pump seepage; right engine-mount collapse; persistent misfire traced to a loose intake-hose clamp; transmission-cooler hose clip released under pressure, dumping all ATF and destroying the automatic transmission; excessive play in all four lower control-arm bushings. The transmission and the other components were replaced 1-2 months before the subframe bro History: A faint clank from the rear suspension first appeared roughly three years into ownership. Dealer service dismissed it as “normal noise,” and warranty would not cover “loud clanks,” so the issue went unaddressed. The noise has grown steadily into the current condition, suggesting long-term subframe corrosion that was never inspected or remediated. No collision, flood, or off-road use; the car has typical Northeast winter-salt exposure. The failure pattern matches subframe-corrosion cases already acknowledged by the manufacturer on this model, although this serial number is not yet included in the official campaign.