MERCEDES-BENZ Complaints

Component/System Failure: The rear subframe on my 2015 Mercedes-Benz C300 failed due to severe corrosion/rusting. The subframe is available for inspection upon request. Safety Risk: This failure created a serious and immediate safety hazard. While driving at highway speeds, the structural integrity of the vehicle was compromised, I had to break and lost control of the vehicle and almost causing a crash. This also posed a danger to other drivers on the road. The condition was severe enough that I believe I narrowly avoided a major accident. Confirmation of Problem: The issue has been confirmed by a Mercedes-Benz dealership service department, who identified the subframe as rusted and structurally compromised. Inspection by Other Parties: The vehicle has been inspected by a Mercedes-Benz dealership. It has not yet been inspected by the manufacturer directly, police, or insurance representatives. Warning Signs Prior to Failure: There were no clear warning lights or dashboard messages indicating this issue prior to the failure. The problem appears to have progressed without visible warning until it became severe. Additional Context / History: Mercedes-Benz has acknowledged subframe corrosion defects in certain vehicles from approximately 2010–2020, but my specific vehicle was not included in the extended warranty coverage. This is the second Mercedes-Benz vehicle I have owned (previously a 2012 model) that has experienced the same subframe failure. I was previously told that this issue had been resolved in newer models, which influenced my decision to purchase this vehicle. Additionally, this vehicle was purchased as a Certified Pre-Owned Mercedes-Benz, which implies it passed a detailed inspection process. Despite this, a major structural component failed. A warranty claim was submitted but denied on the basis of “rust,” even though this appears consistent with a known factory defect.

Driving down Interstate 65 just south of Bay Minette Alabama and doing approximately 70MPH, there was a total failure of the sunroof. This happened where crazing started and then a catastrophic failure of the glass, blowing out the sunroof. This happened in the space of about 30 seconds. It appears to be the exact circumstance outlined in NHTSA Recall #24V874000. Shards of glass entered the cabin, and while there were no injuries, the passenger was hit in the face with debris. The car behind, although hit with some glass, swerved to avoid it and moved on without stopping. No police report was filed. The car was previously inspected by Mercedes under the recall and we were told that the glass was fine and MB closed the recall on this particular VIN. This is a post inspection failure. Mercedes have so far, refused to honor any type of recall work to replace the roof. At this time, I have opened a case with MB USA and await an outcome.

Family and I were driving on the interstate and heard a loud bang (like a shotgun) followed by immediate glass everywhere. The panoramic sunroof exploded. We had to drive 4 hours like this - lucky we didn’t jerk the wheel on the interstate with the noise. Absolutely sickening that this is so prevalent and Mercedes won’t do anything about it.

Hello as of now there was no accidents just read Reading the Recalls it is very serious I take in the vehicle to the Mercedes Benz dealership 4-29- 26 They did nothing but said they would get in contact with me once they receive the remedy

On the morning of April 28, 2026, at approximately 7:30 AM, I discovered that the front panel of the panoramic sunroof on my 2015 Mercedes-Benz GLA45 AMG had spontaneously shattered while the vehicle was parked at my residence in Meridian, Idaho. When I went out to the vehicle in the morning, I found glass fragments distributed across the rear seat area, the rear floor, and my child's car seat. Looking up, I saw that the front panoramic glass panel had shattered. My husband and I conducted a complete walk-around inspection of the vehicle exterior. We found no evidence of any external impact: no damage to the roof surface, body panels, surrounding trim, or any other glass on the vehicle. There was no debris (rocks, branches, hailstones, construction materials, or any other potential impact source) on top of, beneath, in or around the vehicle. The rear panoramic glass panel was intact. Glass fragments were present both inside the cabin and on the exterior surface of the roof and a few fragments were found on the roadway. The car seat where glass fragments fell is regularly occupied by my [XXX] daughter. On this particular morning, she was not in the vehicle only because of a coincidental change in our family's schedule that day, but typically she gets into her carseat independently, buckles herself, and I check her buckles. Thankfully, she was not injured but her car seat now has glass fragments in the seat. I am filing this complaint to document the incident in support of NHTSA's ongoing collection of safety data for consumers. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

rusted rear subframe. unsafe braking and suspension due to this. damage code 35441 47 shows 2008-2015 vins but my vin does not show active recall, yet has the issue

The rear of the car would begin to slip during turns and when brakes were applied. When I had the issue checked out, my mechanic said that the rear subframe has severe corrosion, rust and holes. The subframe perforation is causing instability in the rear wheels, which is a safety issue. I took the car to Mercedes for an inspection and they confirmed the holes in the sub frame,with the inspector stating that the sub frame is "about to fall off". I believe this to be a safety issue as having the wheels or subframe fall off could cause fatalities. This appears to be a manufacturing defect given recalls for the same issue in other models of the 2015 c300. See video of the inspection of my car here: [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

The speed limit indicator included in the software package flashes constantly (approximately once per second), both inside the instrument cluster and in the Heads Up Display. The speed limit shown is almost always not accurate to the current speed limit, even when passing multiple very clear road signs showing the speed limit. The car still flashes when the speed limit it is showing is not being exceeded. Furthermore, when it cannot read the speed limit, the indicator will often flash road signs for other countries. All of this is happening within the field of view of the driver due to the Heads Up Display, causing a visual distraction which could result in accident. Mercedes and the dealer are aware of the issue, and according to my local dealer Mercedes promised to fix it last year, and then promised again to fix it by Q1 of 2026, both deadlines having passed. This same information was corroborated by a post on Reddit from a user who spoke with Mercedes. When I spoke to Mercedes support on the phone they indicated that my particular car was not even supposed to have this road sign feature, so the fact that it is appearing on my car is incorrect.

While driving on I-84 between [XXX] and [XXX] , the vehicle experienced a sudden and complete engine failure with no prior warning. The engine seized, resulting in an immediate loss of power while traveling at highway speed, creating a dangerous situation in active traffic. The driver was fortunate to safely pull the vehicle onto an exit ramp. State police arrived and positioned their vehicle behind it to prevent a potential collision with other vehicles. There were no warning lights or prior symptoms before the failure. The vehicle had approximately 80,000miles and was regularly maintained. The issue has been confirmed by a service center, and the engine may require full replacement. The sudden and unexpected nature of this failure raises serious safety concerns and potential defect issues. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

This vehicle has suffered from persistent, substantial, and uncorrected defects, including but not limited to failures in the 48V mild-hybrid electrical system, lithium-ion battery system, DC/DC converter and coolant system. These defects have substantially impaired the vehicle’s use, value and safety as well as my safety, and remain unresolved despite multiple repair attempts at two separate authorized Mercedes-Benz dealerships in St. Louis, MO. SUMMARY OF DEFECTS •Multiple 48 V battery failures and replacements •Multiple replacements of DC/DC converters and failures •Multiple Coolant System failures •Sudden vehicle shutdowns while driving •Numerous non-start issues •Numerous red warning alerts related to the 48 V system •Multiple towing incidents (One involving the police) Despite extensive repair attempts, including replacement of major components, this vehicle continues to fail and is currently still at Mercedes-Benz of St. Louis unrepaired. These repeated repair failures demonstrate the vehicle cannot be repaired to conform with warranty standards. SAFETY INCIDENT My most recent safety incident: On March 10, 2026, this vehicle shut down in the middle of a busy multi-lane roadway, requiring police assistance and emergency towing due to the safety hazard presented. The vehicle has remained in possession of Mercedes-Benz St. Louis since that date (over 45 days) and remains inoperable and unrepaired. This vehicle had also been towed to Plaza Motors two additional times for the same reasons and was there for many days adding to this amount (See attachments). MULTIPLE DEALERSHIPS/FAILED REPAIRS The vehicle has been serviced by both: *Plaza Motor Compay, St. Louis *Mercedes-Benz of St. Louis Despite independent repair attempts by both authorized dealerships, the same defects persist. This confirms that the issue is inherent to the vehicle itself, not a service related issue.