general problems of the 2012 Mercedes Benz C300

The subframe has developed extensive rust and corrosion, which I believe is a result of faulty manufacturing. This corrosion has severely compromised the structural integrity of the subframe, posing a serious safety risk. The corrosion appears to be inherent to the materials or design used in the manufacturing process, leading to the rapid deterioration of the subframe. There are also no warning lights or failure indicators for this issue. As a result, the subframe is at risk of collapsing, which could cause catastrophic failure of the vehicle's suspension and steering systems. This situation creates an immediate danger to both the occupants of the vehicle and others on the road.

Brake line corrosion.

Took my car for a doorknob repair and was told the whole subframe is rotted. They told me not to drive the car on the highway. The car brakes very hard to the right and always goes right while making cranking noises. Car feels very unsafe. I paid a lot of money for this and own a 2012 C300 4matic.

This is a low mileage car with odometer reading of 25668 (less than 2000 miles per year), used sparingly and always parked in the garage. On 05/07/2024 I noticed brake fluid flowing from the left rear side of the car; on examination this seemed to come from the flexible hose that connects the brake fluid line to the brake caliper. I called my mercedes-benz (mb) dealer and arranged for further inspection and service. The technician identified that the brake fluid lines to the rear were both totally corroded and in need of immediate replacement. Since the lines were embedded behind the subframe it necissated lowering the subframe to access. Other parts were also severely corroded and required replacement. (see attached pdf of invoice) the total cost of the repair was $4,592. 93. The dealership applied a discount of $150. 00 to this for an amount due of $4,442. 93. As an engineer, I believe the material used for the brake fluid lines were unsuitable and furthermore were unprotected for the harsh environment experienced under the car, and I believe mb with all their experience in automobiles manufacturing over the years clearly should have known and forseen this fact; I do believe that mb is responsible for this premature failure of the brake lines of my car aven driven only 25,666 miles to date. I am therefore requesting NHTSA to require mb to reimburse me for the unnecessary expense of the costly repairs. It is only fortunate that this failure was identified in my garage and not on the highway. Please advise me of your resolution. Thank you.

While I was driving my 2012 mb C300 4matic sport sedan in Nov', 2023 with history of regular maintenance, noticed a pretty load knocking noise, shudder and drifting to left a bit when it brakes from the driver's rear side especially on the highways. I took it to our local mechanic who was horrified to report that the sub frame was broken and completely rotten out too specifically rust issue with the rear suspension-rear subframe. He gets other german cars like BMW & Audi even older and more miles in chicago but none have rusted so much as these mb c-class cars. Knowing the dealers wont accept it a manufacturing defect, he was planning to repair it (no chance of wielding that thin metal sheet as the likelihood of breaking it is high). I was surprised to see 2010 chevy impala having a much more robust under the cover protection and no rusting with 115k miles. Information redacted pursuant to the freedom of information act (foia), 5 u. S. C. 552(b)(6).

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 at 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 then stated that he received an unknown manufactured recall for the sub frame assembly where it was then taken to the dealer where the contact was then informed by the technician that the rear brake line had leaked 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 at various speeds, extra brake travel time was needed to stop the vehicle. There was no warning light illuminated. The contact had taken the vehicle to an independent mechanic where the vehicle was purchased, and he was informed that the failure was caused by the new brake pads placed on the vehicle. The contact eventually took the vehicle to a dealer and was informed that the fuel tank and brake lines were corroded; and the contact was provided an estimate for the repair. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 96,000.

I found out about the mercedes subframe failure issue after having problems on the road, that could have killed me, and being warned not to drive anymore by an authorized repair shop because my vehicle was not safe for me to drive. This has caused many other issues with my cars mechanics due to this defect from the mercedes factory.

The left rear weld of the subframe on my 2012 C300 4matic has rotted through and appears to be a manufacture's part defect. I found out about this issue from a brake inspection and told it is a safety concern, which Mercedes Benzes is aware of but has no recalls for the defect.

From the mechanics notes: four-wheel alignment could not be completed. Attempts to align the rear axle were unsuccessful due to flexing/movement in the rear suspension. A brief road test revealed occasional suspension “clunking” coming from the rear of the vehicle. Close examination of every suspension component mount revealed heavy cracking on the passenger side lower drag link subframe mount (see emailed image). The driver’s side low drag link mount location is also starting to show signs of overstress and rust/flaking. This is a known design defect that has been the subject of a manufacturer’s recall in canada. Given the substantial safety impact of this design defect/failure, it is expected that a us recall will be forthcoming. Proper repair of this failure involves removing the entire rear axle/subframe assembly and either rebuilding/re enforcing the subframe or replacing it with a new unit and transferring all the suspension components to the new subframe. A current check of subframe availability is showing nla (no longer available) status from mercedes wholesale dealers – likely due to recent high demand and inability to satisfy that demand. This supply issue may also be playing a role in mercedes’ failure to address this high level safety issue with a us based recall campaign. The manufacturer may be ramping up production of this component to address anticipated need – waiting to announce a recall when it has sufficient parts on hand to execute the campaign. It is strongly recommended that you file an NHTSA complaint for this issue and limit driving until the problem is rectified either independently or under the auspices of a recall campaign. The passenger side rear drag link has not yet completely separated from the subframe but is likely to do so soon which can result in an accident or loss of control as this critical suspension link is responsible for maintaining steering direction of the right rear wheel.

The rear drivers side had a loud chunking/clanking noise while driving and the vehicle was unable to control and break when in motion. Driving was impossible as the breaking component was a total failure and car could not be controlled while traveling down 45-50mph zone. I reduced my speed to 20-25 mph by letting off on the gas to get better control of the car if breaking would need to be suddenly made. I relied on the shoulder to pull off if any sudden breaking was needed. The car was immediately take to be reviewed by a specialized Mercedes Benz mechanic and further inspection proved that the rear subframe on the driver’s (left) side was corroded and broken. The connecting arms are rusted, corroded and rendered the car inoperative. I notified my insurance company as well as car manufacturers corporate office. I researched this issue further and discovered that this reoccurring issue with this make and model. There are a pheletera of recounting of this same issue on various message boards to validate the same issues and callouts I found. The car was taken to the dealership that it was purchased and further inspection showed that the left side subframe/ subframe arms were corroded with rust and broken. The brake lines and fuel tank were equally rusted and corroded. The service manager confirmed that this is defect of the car but it had been part of a recall. I had the car towed for 2nd opinion to another dealership service department to access the car and this callout further validated the corrosion and rust was wide spread and has rendered the car inoperable unless these damages were fixed.

My vehicle was damaged by k and h auto. The electrical unit is malfunctioning, the light is broken on the right side, and the rotors and brakes have been rusted, please have someone attend to this matter. Thanks, and have a very blessed day. Another company by the name of ans towing, towed my vehicle without care and I am now having acceleration issues with my vehicle. The vehicle was dragged through water on October 17-18, 2018.