What 24 owners told NHTSA about the 2023 Mercedes-benz C-class Cabriolet

I am filing a safety complaint regarding my 2023 Mercedes-Benz AMG C43 4MATIC. The vehicle has approximately 23,000 miles. On multiple occasions, the vehicle has abruptly and violently applied the brakes and/or come to a near stop while I was driving on highways and side roads, even though there was nothing in front of me that should have triggered emergency braking. There was no vehicle, pedestrian, cyclist, object, or road hazard present that would justify this braking event. This is not normal braking behavior. The car essentially performs an uncommanded emergency stop or severe deceleration without warning. The force is strong enough to create a serious risk of being rear-ended by vehicles behind me. This has happened at highway speeds and on local roads, making the vehicle unsafe to operate. If a following driver is unable to react in time, this defect could easily cause a crash, injury, or death. The problem appears related to the vehicle’s automatic emergency braking / Active Brake Assist / forward collision avoidance system and possibly other linked driver-assistance systems. The vehicle has already been serviced on two separate occasions for this exact issue, yet the problem has occurred again. Despite bringing the vehicle in for repair more than once, the defect remains unresolved. Because this dangerous unintended braking continues to happen, I cannot continue to drive the car safely with this issue unresolved. On April 1, 2025, I took the vehicle to Aristocrat Motors in Merriam, Kansas for the car slamming on the brakes and beeping when no one was around. The service center calibrated the augmented reality camera and performed a test drive. The invoice indicates that they were unable to duplicate the braking event during the test drive. They ran codes with SDS and found that the augmented reality camera was not calibrated correctly, so they performed a calibration. On December 31, 2025, I again took the vehicle to Aristocrat Motors in Merriam, Kansa

NHTSA ODI 11735812

When going into Reverse the passenger side mirror angles down to see curbs. When putting back into Drive it should be going back up to normal angle, but 20% of the time it does not go back up. If you're driving in the dark you may not know it's reverted back up and get into a car accident. Dealership said there are no issues and a technician stated it goes back up at +9 mph. I've gone over 30 mph driving on public street only to realize it late. I am hoping this gets publicity before an accident occurs due to a defective safety-comfort feature.

NHTSA ODI 11699593

The contact owns a 2023 Mercedes-Benz C300. The contact stated that on occasion while driving at various speeds, the vehicle unexpectedly stopped without the brake pedal being depressed. There were no warning lights illuminated. The vehicle was diagnosed twice by the local dealer, and the contact was advised that the Forward Collision Avoidance sensors needed to be recalibrated; however, the failure persisted. The vehicle was taken back to the same dealer where the vehicle was inspected, and the contact was advised that further diagnostic tests were required to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The approximate failure mileage was 28,000. The VIN was not available.

NHTSA ODI 11680376

My panoramic sunroof spontaneously exploded while driving down the highway, no external impact was made. The glass exploded from the inside out. It made a loud boom, it startled me on the highway resulted me to swerving on the road, which would have put me and other drivers at risk. There's plenty other MB drivers reported similar issues that stated. MB has also settled a class action lawsuit regarding such manner. UNKNOWN There were no warning signs prior to the event. The event spontaneous and sudden.

NHTSA ODI 11678947

On 4 different occasions car brake assist activated causing car to come to an immediate stop and jerk. At stop light as I started to accelerate a left turn car came to an immediate stop almost causing the car behind hit rear end. Brake assist light activated. This happened twice. And twice when in reverse backing out of a parking space and backing into driveway. Dealership notified look at my car and stated they did not see anything wrong. 4th incident happened within 30 minutes after leaving Wilmington Mercedes Benz.

NHTSA ODI 11674663

While driving at 60mph my panoramic sunroof completely shattered. Nothing at all hit the sunroof to cause it to shatter. If my sunshade cover had not been on, the glass would have fallen on me while operating my vehicle. This is not only dangerous but unacceptable. It was also a distraction that could have caused an accident. Mercedes did not make me aware of the class action lawsuit they have with the panoramic sunroofs, and I feel that was neglectful on their part. Upon inspection from a service advisor at a Mercedes Benz dealership, they told me something must have hit it (nothing hit it) and want to charge me $4,000 to fix it.

NHTSA ODI 11662742

The contact owns a 2023 Mercedes Benz C300 equipped with Pirelli Tires, Tire Line: P Zero, Tire Size: 255/35/VR19, DOT Number: [XXX] . The contact stated while driving at undisclosed speeds, there was an unknown bumping sound heard. The contact pulled over and noticed that the passenger's side front tire was flat. The TPMS warning light was illuminated. The infotainment screen showed a reading of the tire 0 PSI. The contact noticed there was a hole in the tire and the side wall was damaged, and the rim was damaged. The contact depressed the SOS button but received no assistance. The vehicle was towed to the residence. The vehicle was taken to a tire center, but no assistance was provided. The contact called the local dealer and was provided information for the tire replacement. The dealer informed the contact that the tires on the vehicle were not correct for the vehicle. The vehicle was not repaired. The manufacturer was contacted, but no assistance was provided. The vehicle and tire failure mileages were 16,000. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11615020

This car has the driver assistance package including Active Speed Limit Assist which is supposed to automatically adjust the speed of the vehicle based on detected speed limits. However, it gets the speed limit wrong an excessive amount of the time sometimes resulting in the car suddenly decelerating which I consider to be a serious safety issue that could result in collisions. In my situation, I have experienced the car suddenly slowing to 40 mph for no reason in an area where the speed limit was 65 mph. I have also seen this problem documented on a number of blogs related to Mercedes-Benz vehicles. When I reported the problem to the dealership, I was told that it was a known issue and was encouraged to turn this feature off. I think Mercedes-Benz needs to fix this known issue for those of us who have cars with Active Speed Limit Assist.

NHTSA ODI 11612912

While driving on the highway I had decided to tilt my sunroof open. When it opened the sunroof completely cracked/shattered discarding tiny particles of glass all over me. There were no previous compromising cracks nor did anything hit my pano sunroof causing this to happen

NHTSA ODI 11606333

The electrical wiring harness of my vehicle completely caught fire making my vehicle stopped working. Manufacture warranty refuses to acknowledge this as an ongoning issue with this models and forcing me to pay for my own repairs this is a danger to anyone driving this vehicle as the car entirely can be caught on fire at any given time.

NHTSA ODI 11596594

Filing complaint on behalf of my sister. She was driving on empty side street around 25mph and the car comes to an abrupt stop. Apparently part of the collision avoidance system, yet nothing in road, on road or in sight. If there was anyone behind her, they would have slammed into the rear end of her car.

NHTSA ODI 11584616

The contact owns a 2023 Mercedes-Benz C300. The contact stated that while driving with the Adaptive Cruise Control engaged, the vehicle decelerated quickly, causing the driver to lose control of the vehicle. The vehicle was not diagnosed or repaired by an independent mechanic or dealer. The manufacturer was not made aware of the failure. The failure mileage was unknown.

NHTSA ODI 11580656

On 2/17/24 the vehicle was parked in front of my house. There is a slight grade. The vehicle had been parked for approximately 1 hour when my neighbor called me to tell me that the vehicle had rolled down the hill and into his storage building. The vehicle rolled on its own. I have video evidence that no one was in or around the car at the time of this occurrence. I also, have 2 eyewitnesses who can corroborate this story. Due to safety concerns, I immediately returned the vehicle to Mercedes. I have .MOV files and pictures JPEG that will not upload for some reason.

NHTSA ODI 11577612

The contact owns a 2023 Mercedes-Benz C43 AMG. While driving into a parking lot at a very slow speed, the braking system suddenly activated, and the vehicle shut off. After restarting the vehicle, the messages "Rear Axle Malfunction", "Active Braking System Limited" and "Inoperative" were displayed. The cause of the failure was not yet determined. The manufacturer and local dealer were notified of the failure. The failure mileage was 5,600.

NHTSA ODI 11572056

The above multiple problems/parts at issue. To include Other/I am not sure. Started at or approximately February 2023. The (Automatic Folding Side View Folding Mirrors before resolution) Malfunctioned 3 separate times before being fixed. During that time the (Cooling System Malfunction Reduced Drive Performance Service Required), displayed 2 separate Unknown Dates on the Dashboard Screen. The MB Dealership Service Diagnostic Check made was not Able to Detect the Trouble and was Never Fixed). On Monday, 08/21/2023, by (USPS) delivered a Mercedes Benz Official Letter Head Dated August 2023, stating that an (IMPORTANT SAFETY RECALL) for my Make and Model was issued. For the (Fuel Pump Impeller Module & Unfortunately, the Remedy is Not Yet Available). August 2023, the (Battery Voltage Level Percentage Warning Light) displayed 2 separate times. Then unknown dates, the front left driver's and right passenger's window were only going down by about 10-25% and up by about 90%, without completely closing. on 10/26/2023, the (Coolant System Malfunction Reduced Drive Performance Serviced Required) displayed. It has been at the Henderson of Mercedes-Benz Dealership to this date because knowing and understanding of the issues and unable to repair the problem. Additionally, being told the fuel pump recall parts not available until May of 2024. Monthly payments are still made, but the vehicle is not or cannot be driven due to the C-Class Sedan Operator's Manual on Pages 26-27, noting this could cause Crash, Injury and/or Death. I (FEAR FOR MYSELF, FAMILY, PUBLIC'S SAFETY & LIFE). The vehicle was brand new build and only has about 2,300 actual miles total. Reasonable time, due process has been given or allowed and being told it is unknown when or how all repairs will be fixed and still owning and not being able to drive the vehicle. Conclusion, I have loss all faith, trust and confidence in vehicle and if all will ever be fixed and (I WANT A TOTAL & FULL REFUND NOW).

NHTSA ODI 11555944

The contact owns a 2023 Mercedes-Benz C300. The contact stated while driving 50 MPH with the Intelligent Cruise Control activated, with no other vehicles or objects nearby, the vehicle inadvertently slowed down. After restarting the vehicle, the vehicle returned to normal functionality but later displayed the following messages: “Active Emergency Stop Assist Currently Unavailable”, and “Active Steering Assist Inoperable”. The Forward Collision Avoidance warning light was illuminated. The vehicle was taken to the dealer but not yet diagnosed. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 6,000.

NHTSA ODI 11544088

The contact owns a 2023 Mercedes-Benz C300 equipped with Bridgestone RFT Tires, Tire Line: Turanza 100, Tire Size: 225/45/R18, DOT Number: VRJ7V4Y. The contact stated that while driving at approximately 40 MPH, the driver's side tire exploded. The contact stated that a "0 PSI driver side front tire" warning light was illuminated. The contact stated that he observed that the driver's side tire had a portion blown out on the sidewall of the tire. The vehicle was towed to a local dealer where it was diagnosed that the blowout had been due to external sources and not tire structural integrity. The manufacturer was notified of the failure. The contact stated that the vehicle was no longer equipped with a spare tire, and the contact was informed by the dealer that any type of spare tire for the vehicle was unavailable for purchase. The contact had been told by the manufacturer that the vehicle had been equipped with "run flat tires" and there was no need for a spare tire. The approximate vehicle and tire failure mileage was 2,000.

NHTSA ODI 11543206

The contact owns a 2023 Mercedes-Benz C300. The contact stated while reversing, the check engine warning light illuminated and the vehicle lost motive power, stalled and shutoff. The contact was able to restart the vehicle, but had the vehicle towed to the dealer. The dealer stated that no cause for the failure was found but updated the software. The failure reoccurred. The vehicle was taken back to the dealer and the contact was informed that the water pump needed to be replaced. The vehicle was not repaired. The manufacturer was not contacted. The failure mileage was 3,900.

NHTSA ODI 11540331

Major safety issue - PHANTOM BRAKING. On 2 separate occasions the vehicle engaged emergency braking while there was no apparent hazard. This phantom braking was very dangerous. This car has adaptive cruise control. It occurred in the exact same spot on Interstate-84 and NE 21st Avenue in Portland, Oregon while traveling east bound. The cruise control was on and engaged in incident 1. Cruise control was on, but not set, in the second incident. First incident was approximately 6/1/23. Second incident was 7/16/23. I have reported to Mercedes Benz Customer service. Case opened #2-42097036640. I will contact the dealership to report as well.

NHTSA ODI 11532743

The Mercedes just slams on the brakes for no reason. It's happened 3x and is very scary. According to Internet posts this is a common problem because of collision assist malfunction

NHTSA ODI 11528225

- December 5, 2022, while driving on I-20 East in Atlanta, Georgia in the evening, at a speed of 15-20 mph my vehicle abruptly came to a stop in the middle of traffic with no warning and no action prompted by me while driving. There were vehicles positioned in front and behind my vehicle. Thankfully, the vehicle behind me was able to slam on its breaks to prevent colliding into my vehicle. - April 7, 2023, while driving in southwest Atlanta in a residential area at a speed of 15-20 mph, while on the phone with one of my work colleagues, my vehicle abruptly stopped while driving past houses with no warning and no action prompted by me while driving. There was a vehicle positioned behind me that was able to slam on its breaks to prevent colliding into my vehicle. - May 5, 2023, while driving in a residential neighborhood on W Wesley Rd in Atlanta at a speed of 10-15 mph in a construction zone, my vehicle again abruptly stopped with no warning. This time, the stop was much more forceful than previous incidents. - May 5, 2023 my car received the following prompt on my screen "Your vehicle has detected a breakdown. Do you want to receive support from Mercedes-Benz Roadside Assistance" - Mercedes assessed my car and reported the following: C111A00 Radar sensor 1 is disrupted by interference from an external transmitter." Then, "NOTE PER OWNERS MANUAL, THE SYSTEM ON THE CAR CANNOT ALWAYS TAKE INTO ACCOUNT ROAD, WEATHER OR TRAFFIC CONDITIONS///BE AWARE OF THE LIMITATIONS REGARDING THE SAFE USE OF THE THESE SYSTEMS///" - The vehicle does not send an alert, forewarn, nor does it allow you to override an automatic emergency break - Mercedes Benz was flippant, dismissive and asked me to resume driving in an unsafe vehicle. I am filing this because they appear to have no regard for human life. I fear for my life and do not want to pass this burden on to someone else -In every instance described above, I contacted Mercedes Benz to make them aware. The contact is requesting to rescind the complaint and does not wish to move forward with the claim.

NHTSA ODI 11524034

First week, the car would take off fast as soon as the brakes were released. Then first time I used the heat there was a crackling sound coming form the side of the center display and it got extremely hot, I was on the FWY driving in the rain. Brakes: Intermittently, when braking, the car speeds up as if shifting to N, problematic in the FWY traffic behind another car, sometimes the brake pedal can be heard rattling really lose underfoot, brakes also used to groan when backing up. Electrical: intermittently, the door/trunk lock, side mirror, garage door opener do not work, and the dash displays change by themselves, the worst is the unreasonably hot center display that burns fingers, and becomes untouchable on hot days. Transmission: seems not to work in unison with the accelerator as sometimes the RPM needle hits 3-4 but the car will not speed up or is sluggish. Other: the car intermittently kicks, like being rear ended, it happens at different speeds and stopped or driving, continuing a few times intermittently for a day or two. Twice have taken the car to MBZ dealership, one for 2 days, another for 10 days, they said they reset everything and all was fine. The issues are intermittent and hard to duplicate for some one who does not drive the car regularly. The dealership has been great but I do not feel they are able to reveal the problems with the vehicle. The car is like a computer with a virus and sometime gives erratic response.

NHTSA ODI 11523001

The contact owns a 2023 Mercedes C300. The contact stated that while traveling over a pedestrian crosswalk, the emergency braking mode was engaged. The accelerator pedal was applied but the vehicle failed to accelerate. The vehicle went into restricted mode. A Hyundai Elantra crashed into the rear of the vehicle. The driver in the Hyundai stated that the brake lights were not illuminated. There was no air bag deployment or fire. A police report was filed. The contact who was occupying the front passenger seat sustained an injury to her neck and medical attention was provided. The vehicle was towed to the local dealer where it was diagnosed that there were no restricted mode codes located. They were unable to duplicate or verify the incident. The vehicle was not repaired. The manufacturer was contacted but no additional assistance was provided. The failure mileage was approximately 2000.

NHTSA ODI 11520942

The contact owns a 2023 Mercedes-Benz C300. The contact stated that while driving at various speeds, the Forward Collision Avoidance system erroneously activated, causing the vehicle to abruptly stop in the middle of the road. The failure occurred on three separate occasions and each time no other vehicle or object was nearby to cause the Forward Collision Avoidance system to become activated. The vehicle was taken to the local dealer who replaced sensors and recalibrated the Forward Collision Avoidance system, but the failure persisted. The manufacturer was not notified of the failure. The failure mileage was 1,000.

NHTSA ODI 11520487