*Median odometer reading when the problem happened, where owners gave one. One complaint can name several problem areas.
Service brakes, hydraulic
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.
Jul 1, 2026 · 39,000 milesForward collision avoidance › Automatic emergency braking
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…
Jun 17, 2026Unknown or other
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…
Mar 19, 2026Forward collision avoidance › Adaptive cruise control
The issue is regarding the âTraffic Sign Assistâ (Ownerâs 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…
Mar 31, 2026Structure › Body
The glass panel between the windshield and the sun roof shattered spontaneously
Jan 5, 2026Unknown or other2 injuries
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.
Nov 8, 2025Equipment › Electrical › Infotainment
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…
Nov 7, 2023Structure › Body
The rear door randomly closes with force unexpectantly. We contacted the Mercedes dealer where the car was purchased and is serviced. They responded it can not be fixed and was an ongoing concern of many owners
Jun 3, 2025
Owner complaints are submitted to NHTSA by the public and are not verified. Shown as filed (NHTSA removes personal details); long reports are shortened.