Which parts fail
Components named in complaints (doors, hood, frame, rust, paint and trim).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2012 Mercedes-Benz C300 owners, lightly cleaned up (personal details are redacted by NHTSA).
The contact owns a 2012 Mercedes Benz C300. The contact stated that while driving 45 MPH, the contact started to lose control of the vehicle while depressing the brake pedal. There was no warning light illuminated. The contact regained control of the vehicle and drove to a dealer. The vehicle was inspected, and the mechanic discovered that the subframe had fractured due to severe corrosion. The contact was notified that the vehicle was unsafe to drive. The contact was provided an estimate for the repair. The manufacturer was also notified of the failure and informed her that 15% of the cost of the repair would be covered. The vehicle was not repaired. The failure mileage was approximately 62,000. The contact stated that their vehicle was finally repaired by the dealer in Dec. 2022. The manufacturer helped pay approximately 13% of the total repair costs.
The contact owns a 2012 Mercedes-Benz C300. The contact stated that while his wife was driving at an undisclosed speed, she heard an abnormal sound coming from the rear of the vehicle. The vehicle was taken to an independent mechanic where it was diagnosed that the subframe wheel assembly needed to be replaced. No warning lights were illuminated. The vehicle was repaired; however, the contact stated that he received an unknown manufacturer's recall for the subframe assembly which it was then taken to the dealer, and the contact was informed by the technician that the rear brake line was leaking and needed to be replaced. The vehicle was not repaired. The manufacturer was notified of the failure and the contact was informed that the VIN was not included in a recall. The failure mileage was approximately 120,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 70 MPH, there was an abnormally loud sound from the rear of the vehicle. The contact lost control of the vehicle. There was no warning light illuminated. The contact was able to continue normal driving once he regained control of the vehicle. The contact scheduled an appointment with an independent mechanic for the vehicle to be inspected. The contact was informed that the rear subframe had detached from the passenger's side of the vehicle due to severe corrosion. The dealer was notified of the failure and informed him that there were no recalls related to the failure on his vehicle. The manufacturer was not notified of the failure. The vehicle was not repaired. The failure mileage was approximately 138,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving approximately 65-70 MPH, he heard abnormal clicking sounds coming from the rear of the vehicle. Additionally, the contact stated that while driving and depressing the brake pedal to come to a complete stop, the vehicle swerved while stopping. The vehicle was taken to an independent mechanic where it was diagnosed that the rear driver's side subframe was severely corroded and fractured and needed to be replaced. The dealer was notified of the failure and informed the contact that the vehicle would be repaired at his own expense. The vehicle was not repaired. The manufacturer was notified of the failure but did not provide any assistance. The failure mileage was approximately 75,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated her son was driving approximately 60 MPH and noticed that the steering wheel was crooked and vibrating. The driver was manually turning the steering wheel for the vehicle to drive straight. The driver also noticed that while depressing the brake pedal, the rear of the vehicle was shaking going from left to right while coming to a complete stop. The driver took the vehicle to an independent mechanic to be inspected and was informed that the rear driver's side subframe had separated from the vehicle due to extreme rust. The vehicle was not repaired. The manufacturer was made aware of the failure. The failure mileage was approximately 115,000.
the Rear Subrame CRACKED while Driving, Almost causing a Major accident with my son in the car as well. This seems to be a MAJOR problem being overlooked and ignored by Mercedes Benz . This repair is going to Cost me $ 3000-$ 5000 Dollars. and the Replacement Subframe is Impossible to find and on Back order ! so Now I'm without a Vehicle for God knows How long ?? I Feel there is No Doubt this is a Defect and Should be Covered by Mercedes Benz and a Recall ! How is this not being investigated is Really Scary. How can a Frame or a Car just Crack ? That's Not safe for ANYBODY !
The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving at an undisclosed speed, he heard an abnormal sound coming from the rear of the vehicle, prompting him to pull to the shoulder of the roadway. After a visual inspection, the contact observed that both trailing arms had become detached. No warning lights were illuminated. The vehicle was taken to an independent mechanic, who determined that extensive frame corrosion had caused both trailing arms to detach. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 143,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated that while driving approximately 55 MPH and pressing the brake pedal, the entire vehicle shifted to the left. Additionally, while driving at various speeds the vehicle was unstable and experienced vibration. The vehicle was taken to an independent mechanic who discovered that the subframe of the vehicle had severe rusting and corrosion and that the vehicle was unsafe to operate. The vehicle was not yet repaired. The local dealer and manufacturer were not notified of the failure. The failure mileage was 95,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated that while her granddaughter was driving the vehicle, there was a rattling sound coming from underneath the vehicle. The vehicle was later inspected by an independent mechanic who diagnosed that the rear passenger's side wheel well had sustained severe rust and corrosion and informed the contact that the vehicle was unsafe to be driven. The vehicle was not yet repaired. The manufacturer and local dealer were not notified of the failure. The VIN was not available. The failure mileage was 115,000.
The contact owns a 2012 Mercedes-Benz C300. The contact stated that the vehicle was making a loud bang sound towards the rear of the vehicle while driving over bumps in the roadway. The contact took the vehicle to the dealer and was informed that the rear subframe and the rear brake line were severely rusted. The subframe was replaced under an extended warranty coverage; however, the brake line was not covered under the extended warranty. The brake line was not replaced. The manufacturer was made aware of the failure. The approximate failure mileage was 110,000.
Body complaints in other C300 years
Frequently asked questions
How common are body problems on the 2012 Mercedes-Benz C300?
NHTSA has 54 complaints about the body & structure of the 2012 Mercedes-Benz C300, 20% of the model year's 266 complaints. The component named most often is body (30 mentions).
Is there a recall for 2012 Mercedes-Benz C300 body problems?
No. NHTSA lists no body & structure recall for the 2012 Mercedes-Benz C300, though it has 6 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2012 Mercedes-Benz C300 body problems start?
Half of the complaints with a recorded mileage happened before about 110,000 miles, and 4% before 25,000 miles.
Is it dangerous?
Owners linked 0 crashes, 0 fires and 1 injury to body & structure problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.