What 584 owners told NHTSA about the 2012 Mercedes-benz C-class Coupe

My vehicle has 70,000 miles. always kept garaged. Told by dealer when taken for the yearly checkup that the rear subframe of the car is totally rotted. Needs replacement. Price $3790. Mercedes would only cover 20% of the cost. There have been recalls in Canada with the same issues. Please investigate as this is a serious defect problem and not a warranty issue as Mercedes is claiming.

NHTSA ODI 11506398

Premature subframe rust, causing the vehicle to swerve when brakes are applied looks to be a trend: https://www.benzworld.org/threads/2012-c300-rear-subframe-any-updates-on-recall.3086018/page-6

NHTSA ODI 11506176

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving at various speeds, the rear end of the vehicle was shaking and vibrating abnormally. While the vehicle was in for routine maintenance, it was discovered that the rear subframe was severely rusted. The cause of the failure was not determined. The vehicle was not yet repaired. The manufacturer was not notified of the failure. The failure mileage was 65,000.

NHTSA ODI 11505118

The left side of rear subframe has rusted out. The right side had been repaired by welding by a previous owner. The damage is still present and can be inspected. The broken bracket is right next to the gas tank and can possibly contact or dent the tank during a hard break or collision. This is a common problem with many people expressing this online and at the 3rd party repair shops. No warning signs were present until the bracket snapped. Extensive rust and corrosion around the area, specifically on the inside of the subframe.

NHTSA ODI 11504516

Issue with my rear sub frame rotting out due to rust almost causing a very bad accident in a hard braking situation

NHTSA ODI 11503802

The contact owns a 2012 Mercedes-Benz C300. The contact stated that while parked, the vehicle failed to start. The vehicle was towed to the dealer where it was diagnosed as having water intrusion. The vehicle was not repaired. The contact referenced the failure to NHTSA Campaign Number: 22V955000 (Fuel System, Gasoline, Fuel System, Diesel). The manufacturer was made aware of the failure. The failure mileage was approximately 109,000.

NHTSA ODI 11502765

Cradle and subframe are completely rusted out. This a widely common issue with these cars and am reading it across several forums. Other c300 owners say they have had the exact same issue and request for the MB dealership to fix it. Instead they are given a quote of nearly $10,000 to fix it. MB is responsible for this.

NHTSA ODI 11502013

During planned car service my mechanics discovered that rear subframe is broken and is not safe to drive anymore. After investigation I found that this is a major issue that Mercedes owners have with this particular model. In Europe for this issue has been issued Recall, however in US for some reason Mercedes don't take responsibility. This is a major Safety hazard with possible fatal consequences.

NHTSA ODI 11500152

Sub Frame broke from rust. Mercedes Benz has acknowledged the issue in Europe and repaired/replaced the part at no charge. Numerous problems and complaints can be found on line indicating that we, the car owner must and can complain to Mercedes for partial or complete support on the repair. But they do not acknowledge the problem in the US.

NHTSA ODI 11499206

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 30 MPH, she started hearing an abnormal sound. The contact stated no warning light was illuminated. The contact took the vehicle to the local dealer, where it was diagnosed with needing the rear subframe to be replaced due to severe corrosion. The vehicle was not repaired. The manufacturer had been informed of the failure. The failure mileage was approximately 120,000.

NHTSA ODI 11498631

I was driving our Mercedes Benz C300 and noticed the braking distance taking longer than normal. Also, the rear end responding differently than normal. We took our Mercedes C300 to Mercedes Benz Dealer to be serviced. The technician looked under the car and found the rear subframe rotted out. The service advisor informed us of this being a known defect. We have to be cautious about driving the car until it's repaired due to the fact of being a serious safety issue. MB needs to recall these vehicles and repair them before someone is seriously injured in an accident. Many drivers are uware their subframe has rotted out. I've taken this car to the same MB shop for 8 years and all in a sudden this comes out of nowhere.

NHTSA ODI 11497482

The sub frame broke in half and the dealership said it is due to rust. The car has been garage kept and not driven much at all. It’s a 10 year old car with only about 55,000 miles on it. It’s been used very gently.

NHTSA ODI 11496830

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.

NHTSA ODI 11496239

Rear Sub Frame Assembly failure. It is available for inspection upon request. Vehicle rear end begins to wobble at speeds above 40 mph. The issue causes steering to become more complicated and the vehicle veers sharply while braking. This issue makes all C Class vehicles with this Sub Frame Assembly extremely unsafe, especially at highway speeds. Vehicle has been inspected by the authorized Mercedes Benz dealership in Indianapolis, IN. Service Advisor stated it's "amazing" that there hasn't been a recall issued yet. Based on this body style there have been roughly 320,000 of these C-Class vehicles sold. If the NHTSA truly cares about safety, they will launch an investigation into this matter. There are no warning lamps or messages that appear prior to this failure.

NHTSA ODI 11495617

I purchased a 2012 Mercedes C300 AWD from a local dealer and have had it serviced annually. Last week I took it in for the annual servicing and was told by the dealer that the rear subframe had corrosion /rust and the car was not safe to drive. I asked if it was covered under a recall and they said not by Mercedes at this time.They provided a repair estimate that is quite high and close to the appraised value of the car. I asked if there were any options available through Mercedes or the dealer and they confirmed not at this time. I have read many articles related to this problem and imagine there are many complaints on file at NHTSA. This is obviously a serious safety issue and currently Mercedes is not taking responsibility and directing the costs to their customers. In addition there is a subframe parts shortage and it could take weeks to fix. I'm requesting that this be listed as a recall item by Mercedes.

NHTSA ODI 11494292

The contact owns a 2012 Mercedes-Benz C300. The contact stated while driving 35 MPH, the contact heard an unusual noise coming from the rear of the vehicle. The vehicle was taken to the dealer, and the mechanic stated that the rear subframe was rusted and the passenger’s side rear control arm was detached from the subframe. The vehicle was repaired. The manufacturer was contacted and stated there was no recall for the failure. No other assistance was offered. The failure mileage was 43,960.

NHTSA ODI 11492564

Corroded rear cradle driver side. Causing instability driving. Cradle on back order for months according to local Mercedes parts department

NHTSA ODI 11492611

Applied brakes coming down a slight grade and vehicle made a clunking noise and became unstable. Pulled and pitched as brakes were applied and released. Upon checking brakes it was very visible that the rear subframe had failed on the right side and the left was severely compromised. I hard braking situation would have resulted in a crash… The severe damage was not visible a week ago until it rotted out from the inside and failed under load.

NHTSA ODI 11492451

As per an inspection by my mechanic, the rear sub frame of the vehicle has cracked due to rust corrosion and subsequent metal failure. I first noticed the issue when there was a thumping sound over bumps and the car started to swerve when applying brakes on the highway, quite a scary situation as I thought the brakes were failing. The car has 78000 miles and has had all maintenance done. The is no other rust on or underneath the car. According to my research on Mercedes-Benz owner forums I discovered that it is a common issue and that, so far, Mercedes Benz has not issued a recall in the US. According to these forums Mercedes has issued recalls in other countries (although I have not confirmed this point). The estimated cost to replace the sub frame is $3000 including labor and there is an 8 to 10 week backlog for the part due to the number of failures occurring. In the meantime I cannot drive the vehicle as my mechanic has told me that the car is not safe to operate.

NHTSA ODI 11492253

This issue concerns rear Sub Frame corrosion. My car has always been serviced at the Mercedes Benz dealer where it was purchased as recommended. Upon recievieing my car after a service I was informed that the subframe in my car was badly damaged by metal corrosion. In fact I was told that the car was unsafe and should not be driven as total failure would likely cause lose of control of the vehicle. I was offered a repair quote in excess of $5,000 to replace the rotten subframe. I have since found that this failure is common the the model and many cases have been reported. In Europe and Canada recalls have been issued. Cases in the US are apparently felt with on a "case by case" basis. I see this as a serious safety concern for our highways. Failure is common from reports and and serious accidents surely possible. I have removed my car from service, but many are being driven right now. Mercedes Benz is aware of this and is doing nothing to date to take responsibility for this design/construction defect. I add my voice to the many that I hope have contacted you with concern.

NHTSA ODI 11492281

The contact owns a 2012 Mercedes-Benz C300. The contact stated that upon taking his vehicle to a dealer for maintenance repairs; he was provided an estimate for the repair of corrosion to the rear subframe of the vehicle. Upon investigation, the contact discovered that the failure could lead to a potential braking system failure. The manufacturer was notified of the failure and informed him that there were no recalls on the vehicle. The vehicle was not repaired. The failure mileage was approximately 97,000.

NHTSA ODI 11491578

I have a 20212 Mercedes C300 with 70,000 miles. I took it into the MB dealership for inspection and was told that the rear subframe was rusted through. The subframe's failure also caused the brake lines to rust to the point of needing to be replaced. The subframe repair will cost $5,900 and the brake line replacement will cost around $1,200. The dealer told me the car couldn't be driven safely, so I had to leave it there to be repaired. There were no interior warning alarms about the structure or the brakes. According to forums on Benzworld.org, this is a known problem on these specific cars and the component is replaced for free by MB in Europe.

NHTSA ODI 11491185

The rear subframe rusted and completely cracked. The car started to shake violently while I was on the highway. Fortunately I was in the right hand land and was able to slow down. I was driving in the car with my mother. My understanding from the mechanic is that we were lucky not to be killed or hurt anyone else. The frame is completely cracked. I called the local dealership and they said this is an extremely common problem. So common they have multiple vehicles on the lot waiting for parts, and the waitlist is indefinite. There were absolutely no warnings on the car.

NHTSA ODI 11491215

Car is leaking gas very dangers . I contact Mercedes dealer regarding the recall on this type of Mercedes i have and they said only vehicles manufactured from April 18, 2011, through July 12, 2011. Mine was before or after , and they refuse to give me the exactly date for my car manufacturer. Car I use for Uber , and i don’t have any other income . If someone just through away a cigarette in parking lot might cause a big problem in the building and others cars in parking

NHTSA ODI 11490508

I went to my dealership for a routine yearly service appointment, which I do regularly, along with yearly inspections. My car was purchased new to my liking in 2012 with input from my late partner who passed before I received it! I waited quite some time to get my gem. When it arrived, I had all I could do to drive it, given my loss. I garage it every day for the last 10+ years, never left it outside, it is pristine, only has 64,000 miles on it. To my disbelief, was informed by the MB technician yesterday that I have corrosion on my left rear sub panel, and that I should not drive it and consider a trade-in - NO WAY!! And that the part would cost me over $4,800 to replace and it would not be available until February 2023. So, I should drive another car, which I do not have!!!!! After researching, I am beyond disappointed that this is a known MB manufacturer's defect that has gone this far, customer action needs to be taken!!! My local car dealership states they knew nothing about this, however; pointed out a number of Mercedes C300 in their parking lot sitting with the same life-threatening issue. They were eager for me to talk to sales for a trade-in. Go figure this strategy, NOT. I have had three Mercedes Benz which I love, I do not want to part with this gem, but my need to . . . Please do something . . . Safety and Life matters

NHTSA ODI 11490071