2023 MERCEDES-BENZ GLC 300 Complaints

The contact owns a 2023 Mercedes-Benz GLC 300 4MATIC. The contact stated that while driving at an undisclosed speed, the brake pedal was depressed; however, the brake pedal felt as if it had released, and the vehicle failed to stop as needed. The contact stated that the failure was a recurring failure. The dealer was contacted but could not duplicate the failure. The vehicle was not diagnosed or repaired. The manufacturer was not made aware of the failure. The failure mileage was approximately 39,000.

My 2023 GLC300 suffered a severe, unprovoked emergency brake deployment in traffic, nearly causing a pileup. on [XXX]. The car has only 14,500 miles and has a chronic history of dangerous, unprovoked Active Brake Assist deployments. It broke down twice in its first month of ownership for other reasons, slammed on the brakes during a left-hand turn last year, nearly causing an accident and on [XXX] executed a violent, full-lock emergency stop from 25mph in light traffic with no obstacles in sight, nearly causing a multi-car pileup and putting me thru the windshield. The car was towed to MB of Boston in Somerville under factory warranty on [XXX]. I have refused to drive this hazardous and unsafe vehicle, the Dealer did a quick factory update and an a clean erase of the following code, Code B229BF9, but I have refused to take it back util they have proven to me that this dangerous issue has been fully resolved, I am a [XXX] with a perfect driving record and I frequently drive this car on the highway and I am very fearful the car will do it on the highway which would be catastrophic to me and other motorists. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I purchased a new Mercedes Benz GLC300 2023. Last month, my friend and I were driving on I75 in Florida when we heard what sounded like a loud boom or gunshot. We quickly discovered that my sunroof had exploded. The sunroof was closed, and fortunately so was the sunshade, as large pieces of glass flew off the roof and smaller shards of glass collected on top of the sunshade. My friend and I were fortunate to have not been insured and were able to safely navigate the vehicle to the side of the road to assess the damage. In contacting the MB dealership, I learned that the sunroof is considered "glass" and thus not covered under warranty even though the vehicle is only 3 years old with less than 50,000 miles. What is more concerning to me is that the roof was not under a recall, and there have apparently been other MB owners that have experienced the same issue with class action lawsuits pending. My insurance company covered the repairs following payment for the deductible. This huge safety concern is that we could have been seriously injured by flying and/or falling glass. I write to express my deepest concern over the safety issue the exploding roof presents-the cost of repair relative to what could have happened is minor. Thank you for the attention to this matter.

The issue is regarding the “Traffic Sign Assist” (Owner’s Manual page 221) feature of the Adaptive Cruise Control System. Vehicle will be made available if requested. The function of the "Traffic Sign Assist" is to monitor roadside "Speed Limit" signs and the cruise control will increase or decrease speed to stay within the permissible legal speed limit. The system worked except occasionally it would change the indicated permissible speed limit on the instrument display when there is no corresponding roadside speed limit sign and the permissible speed limit for that stretch of roadway is unchanged. When this happens, suddenly and abruptly, the vehicle display would indicate a "phantom" Higher or Lower Speed Limit sign and rapidly and abruptly accelerate or decelerate. Again there were no roadside signs posted indicating a higher or lower speed limit! The risk is potential for rear end collisions from or to other traffic due to the abrupt acceleration or deceleration. when we returned home from a 4556 mile road trip, we took the vehicle to the Mercedes dealer for routine service and mentioned this to the Service Advisor. He indicated that when this defect is reported their solution is to deactivate the system. I don't feel this is adequate since another driver could reactivate the system through the settings. It has not been inspected by anyone except the dealer. There were no warning lamps, messages or other symptoms before the display changed and the vehicle abruptly accelerated or decelerated.

The contact owns a 2023 Mercedes-Benz GLC300. The contact stated that while driving at an undisclosed speed, the speed limit warning system failed to function as intended. The contact stated that while driving 60 MPH, the Heads-up Display (HUD) illuminated a red light and an unknown message about driving too slowly was displayed. The contact stated that the red light illuminated and flashed intermittently. The vehicle was taken to the dealer, and the contact was informed that the failure was common with the vehicle. The vehicle was not repaired. The contact stated that the failure persisted. The contact asked if the speed limit warning system could be deactivated, and the dealer was informed that it had to be approved by the manufacturer. The manufacturer was made aware of the failure. The contact was referred to the dealer for assistance. The contact stated that the dealer and the manufacturer offered no assistance. The failure mileage was approximately 12,000.

There are two issues 1) Unsure of the exact date, but about a year or two ago we were driving our car and the car's automatic break system went into effect on a typically busy, 3 lane road despite there not being any cars in front of our vehicle. We took it into the dealership, who confirmed the issue and told us that sometimes the automatic brake mis-identifies the metal plates in the roads to be vehicles. Had there been a car driving behind us at the time this was happening, it could have been a major accident as the speed limit on that road was 45mph. Additionally we had our [XXX] in the car. There were no warning lamps, messages or symptoms of the problem prior to failure. 2) Recently we have been having a warning sign on our car that says the 12v battery is low, even though it should not be. Historically this would tell us to drive our car around so the battery wouldn't die, but this would sometimes turn on even after a 30+ minute drive. It was turning on every single time we turned the car off, so we brought it into the shop. While in the shop, the dealer provided us with a brand new GLC 300. I took this GLC 300 to my son's daycare to drop him off and when I returned to the car I received an error message "48V battery service required" and could not turn on the vehicle. This brand new vehicle left me stranded. While I was safe at my son's daycare, this has caused me to have significant concerns around the safety and reliability of these GLC300s. We are planning on taking our 2023 GLC 300 on a 6 hour road trip with our [XXX] old and [XXX] old and I am very concerned about the car not starting if we stop for gas. What if we get stranded in a small city along the way? INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

I purchased a brand new GLC 300 on May 25, 2023. By June 2, 2023 I was already stranded due to a 12V battery electrical system failure. Since then I have been stranded 8 total times and the vehicle has been in the service department 14+ times for repeated electrical issues (8 of those visits were related to the same 12V battery electrical system failures. The battery was reportedly replaced in 2024-shortly thereafter I began experiencing issues with the collision assist malfunctioning. The alarms would sound seat belt tighten and brakes lock up while driving on the interstate. The theft deterrent alarm wound sound in the middle of the night without provocation. The panoramic roof would malfunction. The air vent disintegrated. In August 2025, the collision assist malfunctioned causing the vehicle to steer off the road resulting in a blow out. It has not been driven since.

When loading groceries in my trunk, the door randomly closes on my head. The last time this door closed while we were loading, I tried stopping it with my hand, by holding it, so my spouse doesnt get smashed, and it will not stop at all. There needs to be a safety feature installed to stop this trunk from closing if a person is underneath it. I fear that a child or an elderly person wont be able to move fast enough and will be severely harmed by this.

Vehicle has a significant engine oil leak without being driven. Engine oil electronic meter still shows engine oil to be in "Ok" range. Vehicle is 2023 with only 19680 miles and is rarely driven till the last 2 months. Other 2023 Model Year MB GLC300's manufactured at the same Bremen Germany plant are already being recalled for engine and fuel leaks, however, this one is not on the list. This vehicle is also the 2.0L Inline 4 engine and may be the same engine as the others being recalled. The others are recalled due to an imperfect seal between the high pressure fuel pump and the tandem oil pump. My vehicle is leaking engine fluid, likely oil at a significant rate without having been driven in any unsafe manner or much use.

The contact owns a 2023 Mercedes-Benz GLC300 4Matic. The contact stated that while driving at various speeds and coming to a stop, the vehicle skidded or slid and felt like it had been rear-ended. There was no warning light illuminated. The vehicle was taken to the dealer, but the failure could not be duplicated. The contact stated that the infotainment system was inoperable intermittently. Additionally, the contact stated that while driving 40-50 MPH and depressing the accelerator pedal, the vehicle failed to respond. The contact merged to the right lane to be able to pull over as necessary. There was no warning light illuminated. The vehicle was taken to the dealer to be diagnosed, but the cause of the failure could not be determined. The contact stated that the failure had recurred intermittently. The vehicle was taken back to the dealer. The vehicle was not diagnosed or repaired. The manufacturer was notified of the failure. The failure mileage was unknown.