What 23 owners told NHTSA about the 2024 Mercedes-benz GLC Coupe

While driving the vehicle the engine started running rough, check engine light illuminated and it would not accelerate above 40 mph. There are 29,100 miles on the vehicle, it's been serviced on schedule by Mercedes and is owned by me since new. It is especially concerning due to the acceleration topic which could have been catastrophic if I were trying to merge into traffic. Dealer service say the camshaft bearing needs to be replaced. It seems this is very premature for the mileage on the vehicle.

NHTSA ODI 11741752

While driving my 2024 Mercedes-Benz GLC 300 on California highways, the vehicle has repeatedly experienced sudden uncontrolled deceleration, unexpected transmission downshifts into 2nd gear, severe transmission jerking, and complete loss of accelerator response. The first major incident occurred on March 7, 2025, while traveling on Interstate 5 at approximately 70 mph. The transmission suddenly jolted and downshifted directly into 2nd gear. The vehicle immediately lost power and slowed to approximately 20 mph without warning. I exited the highway and restarted the vehicle before it temporarily resumed normal operation. A second major incident occurred on May 7, 2026, while driving on Interstate 5 near Flag City, California at approximately 65 mph. The vehicle suddenly decelerated uncontrollably to approximately 20 mph. The transmission again shifted directly into 2nd gear, and the accelerator pedal became completely unresponsive. I was forced to make an emergency stop on the shoulder of the freeway with hazard lights activated due to the risk of being rear-ended by high-speed traffic and trucks. A third incident occurred on May 13, 2026, while accelerating onto Highway 99 in Modesto, California. During a shift from 4th to 5th gear, the transmission jerked violently and the vehicle suddenly lost power while merging into highway traffic. The vehicle has been taken to Mercedes-Benz of Stockton multiple times for diagnosis and repair attempts. The dealership has performed software updates and extensive testing, and dealership personnel have personally verified the transmission defect during road testing. Mercedes-Benz engineering has also become involved in the diagnosis process. However, the defect remains unresolved. This defect creates a serious highway safety hazard due to sudden loss of propulsion, uncontrolled deceleration, and loss of accelerator response while driving at freeway speeds.

NHTSA ODI 11740380

3/31/26 2pm After highway driving - 3 miles/35 mph tried to brake- Immediately something was wrong with the brake as and it felt spongy/mushy/unresponsive. Car did not slow until I pressed the brake fully to the floor. The car did stop &was alarmingly unresponsive. Around this time,noticed the white BRAKE light illuminated. Continued to drive - terrified. Had to brake VERY HARD to get car to slow/stop. at home, Quick google search had me try turning on and off parking brake - tied this 5-6 times and white BRAKE light went off and I could brake/stop car. Bought car to Mercedes for service for 4:20 appointment - expressing incredibly strong reservations to Will Bane -and fear about driving car. He assured me as it is braking it should be fine. 04/01/2026 -notified car was ready for pick up/text stated: "Service is complete, everything looked good on the inspection report. No codes in the system for the brake concern and the brakes are currently working as designed" at pickup - and prior in text to will bane - i expressed significant concern about future braking issues. was told it was a "software issue and they updated it" and given a card for roadside assistance There was a recall campaign (2026010002/25p5496612) and codes were cleared as part of this unrelated recall. Brake fluid exchange was performed PRIOR to brake diagnosis Bottom line - I have significant concerns about braking.

NHTSA ODI 11730496

The vehicle has an ongoing transmission downshifting malfunction. The powertrain unexpectedly downshifts while driving, causing sudden changes in speed and unstable vehicle behavior. The issue can be inspected at any time, as the defect occurs intermittently and has not been repaired. This malfunction puts my safety and the safety of others at risk because the vehicle can slow down abruptly or shift aggressively without any input from the driver. This can create dangerous situations in traffic, especially at highway speeds or during acceleration. The problem has been reproduced and observed multiple times by the Mercedes-Benz dealership. I have taken the vehicle to the service center repeatedly for this same issue. Most recently, the vehicle remained at the service center for 10 consecutive days, but the defect was not resolved. The vehicle has been inspected by Mercedes-Benz technicians on several occasions. Despite multiple repair attempts, the issue continues to occur. There were no warning lamps or dashboard messages prior to the malfunction. The issue first appeared months ago and has persisted despite repeated service visits and repair attempts.

NHTSA ODI 11700853

•Incident Details: •Both sudden shutdown incidents •“12V Battery” warning (first incident) •“Stop - Switch Off Vehicle” warning (second incident) •That it happened with children in the car on a tollway Safety Concerns: •Loss of power steering/braking •Risk of collision •Repeated failures on a 1-year-old vehicle

NHTSA ODI 11677934

I am writing to report a critical safety issue with my 2024 Mercedes-Benz GLC300, VIN: [XXX] , which I purchased on [XXX], from Mercedes-Benz of Walnut Creek, CA, with 9,500 miles. On [XXX], while driving on [XXX], the vehicle suddenly lost power, the transmission downshifted to 2nd gear, and the accelerator became unresponsive. I was forced to drive at 20 mph for 20 minutes on a busy freeway, posing a severe risk of a rear-end collision. I managed to exit the freeway, but this incident could have resulted in a serious accident. This failure may be related to prior recalls of the 2024 GLC300, including issues with a defective 80-amp fuse (February 2024) and a loose 48-volt battery ground connection (March 2024), both of which can cause power loss. I urge the NHTSA to investigate this incident to determine if it warrants an expanded recall or further action to protect other drivers. I have notified Mercedes-Benz of Walnut Creek CA and Mercedes-Benz USA, demanding an investigation and a refund under the California Lemon Law. Please confirm receipt of this complaint and provide an update on any investigation. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11647082

I am experiencing auto braking when there are no obstructions near or around the vehicle. The auto braking is random but occurs fairly often. It is very unsettling and makes me very nervous while driving my brand new vehicle. This happens without warning and can definitely put myself and my passengers as well as passengers in the vehicles around me at great risks of collisions.

NHTSA ODI 11645213

Attention Assist System Suspended notification comes on randomly on vehicle while driving, rendering driver defenseless with regard to safety warnings that would otherwise be in effect, such as blind spot assist, attention assist, which are vital components for safe driving. This has happened on numerous occasions, most recently on 12/06/2024 while driving under destination route guidance. It has also happened when car was stopped to retrieve mail at residence mail box and, at other times for no apparent reason, while driving. Each time when engine was restarted the dashboard read 'System suspended' and continued to do so until car was returned to dealer. This vehicle was purchased on 12/21/2023 and with less than 350 miles began repeated problems with warnings, the first of which was "Check engine"on 02/02/2024, as car was running rough. Car was repaired(dealer determined cause was electrical/software error, fault code) yet before driving out of the dealership the same 'check engine' warning reappeared and vehicle had to be returned to service that same day for the same problem. Since that date in 2023, this vehicle has had numerous seemingly computer related issues that render it unreliable as to the safety devices this vehicle features that should always be maintained. On 03/21/2024 with less than 950 miles the fans remained running after shutting vehicle off and a message appeared stating" cooling system malfunction/reduced drive performance" with a red triangle on dashboard. Dealer determined the cause was 'SOFTWARE" At this point I am concerned that this vehicle is over engineered with computerized options that randomly fail. On another occasion the lights on one side may have been on overnight. The lights (courtesy lights) were on on the right side overnight in garage. My safety is continuously at risk whenever a warning appears.I replaced my GLK specifically to have Blind Spot Assist, PRE-safe, Attention Assist, Active distance assist and other features.

NHTSA ODI 11629760

When stopped at a light or stop sign, Vehicle will Jerk forward as If hit from behind. Very surprising and dangerous. Very intermittent. The has happened many times. Vehicle will at times have rough downshifts. Ie. overdrive (9th) to (8th) gear. also intermittent. This has happened multiple times. Vehicle was taken to the dealer twice for a total of 50 hours in the shop. The first service time no problem was found, diagnostics did not show problem. Aug 22 to Aug 30, 2024. The second service time Oct 3 to Nov 14, 2024. Problem was duplicated by the technician. Vehicle diagnostics still did not show a problem. Technician replaced the transmission valve body, did various software checks at the request of the factory. The engine control unit was then changed based on data supplied to the factory. At this point technician checked the car and dealers believes car is fixed. Vehicle has been returned to us on Nov 14 2024. We have requested the vehicle be bought back or replaced.

NHTSA ODI 11625278

The reverse sensors are faulty, causing the GLC300 model to randomly auto-brake while going in reverse. My driveway is flat and long with no significant grade changes and this has occurred at another location as well with similar topography. There are no obstructions present nor any significant grade changes, the vehicle auto-brakes not everytime, happens out of the blue once every 8-12 tries. My new vehicle has been checked out by Mercedes-Benz of Cary service department 2 times, since buying new April 2024. They brought my car out to my house themselves and experienced the auto-braking first hand. They brought out a second GLC300 and it auto-braked as well. The technicians have calibrated, and updated the sensors to no avail. My driveway is long and flat with a slight slope at the end, but it happened to me at my friends house who's driveway is all flat. This is a serious safety risk for me and all passengers. It makes everyone tense not knowing next time it may happen. No matter the revering speed, or if you keep your foot on brake lightly as you are backing up, the glc300 randomly will auto-brake without any warning lights or sounds. The tires screech, it locks up in an instant. It is frightening and we are scared to anticipate the next occurrence or risk bruising our body or head injury. Even when I manually over-ride the rear and/or surrounding sensors, turning them off temporarily as I back up in reverse- the car will still auto-brake. Mercedes has yet to agree with me that this is a safety issue and on 11/8 asked me to pick up the car. I refused until the issue is fixed. They still have my car in service, it has been 3 weeks since 10/18/24. This was the 2nd time I brought in in for this issue since I bought new March 30 2024. I called corporate to ask them to buy back the car if the issue cannot be fixed, they have yet to respond.

NHTSA ODI 11624989

There wasn't a field for my exact issue but my exact issue along with many others is the lack of power when accelerating in first gear. The car has an extremely numb feeling when starting out in first gear and does not takeoff like it should. There have been many Times where I accelerate and the car hesitates then I get a transmission jolt Or the car just does not accelerate immediately when I push on the gas from a stop. This is causing me to not pull out in front of cars in fear the car will hesitate which is a safety issue. this has been going on ever since we got the car a few months ago. The dealership says the vehicle is "operating as designed however this is a poor excuse" i've had owned dozens of vehicles in the past 28 years and not one of them has had poor acceleration like this. I've owned cars with a quarter of the horsepower of this vehicle that accelerate better from first gear.

NHTSA ODI 11617155

Passenger backseat seatbelt would not release under any circumstance. I tried turning the car off and on again. Checking settings on the screen and even releasing the seat a bit. Pushing the red button on the buckle did nothing. Pulling did nothing. Eventually had to cut the seatbelt to get the passenger out. And it is still stuck in the buckle.

NHTSA ODI 11613147

OUR SUV IS 6 WEEKS NEW AND WAS PURCHASED NEW AT THE MERCEDES DEALERSHIP. REAR HATCH: WHEN STANDING BEHIND VEHICLE REAR DOOR HATCH CLOSES RANDOMLY WITH NO WARNING OR BEEP. CLOSES VERY QUICKLY AND HITS HEAD VERY HARD. FEET ARE NOT NEAR THE BUMBER WHICH ELIMINATES THE REAR FOOT ACTION THAT CLOSES THE HATCH. WHEN THE HATCH HITS YOUR HEAD IT COULD KNOCK YOU OUT ESPECIALLY IF YOUR EDERLY OR A CHILD. ALSO IF YOU TRY AND STOP THE HATCH COSING ITS VERY STRONG AND TAKES A LOT OF STRENGTH. WHEN YOU USE THE REMOTE OR BUTTON IN CAR TO OPEN HATCH IT OPENS SO FAST AND BEEPS TO LATE TO ALERT DOOR IS OPENING. VERY DANGEROUS. THIS PROBLEM HAPPEN SEVERAL TIMES AND IS RANDOM. THE LAST TIME IT HAPPEN WAS SUNDAY 9-1-24 WHILE LOADING GROCERIES AT COSTCO

NHTSA ODI 11612085

The contact owns a 2024 Mercedes Benz GLC 300. The contact stated that while attempting to park, the vehicle experienced unintended acceleration causing the contact to lose control of the vehicle and crash into a wall, another vehicle, and two poles where it came to stop when crashing into the second pole. During the unintended acceleration, the contact depressed the brake pedal to control the vehicle however it failed to respond. No air bags deployed. The contact sustained chest, neck, and back injuries and an ambulance transported her to a hospital. A police report was filed. The vehicle was towed to an independent mechanic by the insurance company. The vehicle was not repaired. The dealer was not contacted. The manufacturer was not made aware of the failure. The failure mileage was approximately 97,000.

NHTSA ODI 11604088

I purchased the car brand new from my local dealership and 3 months after purchase my windshield cracked. I had the entire windshield replaced with an OEM windshield on 5/7/2024 and yesterday I got another chip/crack in my windshield. I have only had my car less than 8 months and already had 2 cracks/chips. I owned my previous Mercedes over 6years and never had an chip or crack. This has to be a defect in the windshield. My friend also just purchased a 2024 GLC 300 and it's only 3 months old and her windshield is also cracked. I look forward to hearing from you.

NHTSA ODI 11597905

The contact owns a 2024 Mercedes-Benz GLC300. The contact stated that while driving at an undisclosed speed, the audible alarm activated and several warning lights illuminated. The contact stated that all the warning lights went off except the check engine and the low-battery warning lights. The vehicle was taken to the dealer. The vehicle had not been diagnosed or repaired. The contact stated that the vehicle was previously taken to the dealer on three occasions because of electrical or software failure. The manufacturer was made aware of the failure and a case was filed. The failure mileage was approximately 2,174.

NHTSA ODI 11578547

Check engine light appears, also a blue engine and a turtle. The dealer is aware, they have had it 3times for the same issue and this time 23 days and counting. Currently Mercedes has no fix. I purchased the veh 30 Nov 23- first appeared 16 dec and continued going on and off.

NHTSA ODI 11574918

When driving the car at night with the headlights on, you notice a dark, thin object illuminated from the left front headlight approximately 50-75 feet ahead of the vehicle that will move as the steering is turned, either left or right. It looks like a thin pedestrian moving into the path of the car. I noticed this defect within the first few weeks of ownership. I took the car to the dealership and showed my pictures of the lights with the shadow at night to two Mercedes Benz of Sarasota employees. The dealership ran multiple diagnostic tests and determined the car was operating as designed. While the dealership had my car, two employees at the dealership noted they had relatives who had 2024 Mercedes Benz vehicles and had noticed this same issue. They also received the same explanation that this was the design of the headlights. It is concerning, as it could cause a driver to swerve or otherwise create an issue that leads to an accident. I request NHTSA look into this headlight issue and encourage Mercedes Benz to fix this before an accident happens. I have uploaded the work order documents from the dealership. I have uploaded a picture of the shadow reflected on a car ahead of me to show the shadow up close.

NHTSA ODI 11574540

The contact owns a 2024 Mercedes-Benz GLC300. The contact stated that upon starting the vehicle, the check engine warning light illuminated. The vehicle was taken to a dealer and the contact was informed that the 48V bolt battery had caused the check engine warning light to illuminate. The contact was informed by the dealer that the temporary fix would be to reduce the battery charge to 25% then charge the battery to 75%. The check engine warning light returned soon after the fix and the contact was informed that there was no permanent fix for the defect. The manufacturer had yet to be notified of the failure. The vehicle had yet to be repaired. The failure mileage was approximately 1,800.

NHTSA ODI 11566466

Brand new 2024 GLC300 4MATIC with less than 750 miles. Check Engine light came on with no error message explanation. Brought it in to dealer for service - Found fault code POA7F00. Dealer followed LI54.10-P-077250. Cleared codes. Check engine light is still on with no resolution to problem at this time. Was told to ignore and keep driving. Driving with check engine light illuminated is a safety concern for me.

NHTSA ODI 11566604

Brand new '24 GLC300 4MATIC. Engine light came on with no error message. Brought it in for service. Miscellaneous engine repair states: "Found current code POA7F00 in drivetrain control unit. Followed LI54.10-P-077250. Cleared codes. Drained 48V battery to below 25% SOC. Charged vehicle to 70% SOC. Job complete." Service foreman mentioned that the service performed may not resolve issue. He contacted Mercedes-Benz Engineering and said no fix at this time and no ETA. Left service with no more engine light on. However, it didn't take long, and the engine light came on again. I called service again, and I was asked to take the car back in to be sure it is not anything else. Took my vehicle back, and service foreman diagnosed the issue. Code is the same as before with issues on the 48V battery. Service foreman is unsure of the exact issue. Mercedes-Benz Engineering did not provide details of the problem. I believe this issue poses a safety risk without knowing for sure what is the real cause and what might be the effects on the vehicle. This GLC is my family daily use, and it has become a big safety concern on the road. Service was very helpful and accommodating with my vehicle's issues. Unfortunately, fix is unknown from Mercedes-Benz to be able to resolve. I have also called the Mercedes-Benz Customer Care, 800-367-6372. Unfortunately, there is nothing they can do. I've asked to open a case. Case # [XXX] INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

NHTSA ODI 11566165

2 SEPERATE ISSUE DIGITAL LIGHTING FAILED, THEN 2ND ISSUE WHICH IS STILL BEING WORKED ON, BEEN A WEEK WITHOUT THE VEHICLE WHICH IS ONLY A MONTH OLD WITH 1100 MILES ON IT, THE ENTITE SYSTEM ISNT WORKING WITH LOTS OF CODE ERROR MESSAGES AND WILL NOT START. THE CURRENT UPDATE FROM MERCEDES IS THEY STARTED A CASE AND TESTING THE VEHICLE AFTER REPLACING THE POWER TRAIN. THE TECHNICIAN AGREED THIS IS NOT NORMAL FOR SUCH A BRAND NEW CAR. I AM CONCERNED FOR MY FAMILYS SAFETY AND THINK THIS IS A LEMON

NHTSA ODI 11564146

After giving a pressure to the brakes, the car feels like the brakes are being slipped towards the end, so I have to hold the brakes hard at the end. I have tried different models of Mercedes such as E class but the brake of E class works exactly opposite from GLC 300. When I give a pressure to E class, first it will stop slowly and towards the end, it will stop more aggressively. When I drive GLC 300 on highway, I had to make several sudden stops because I couldn't estimate the brake range. I made several different people to drive my car, and they felt the same. I have reported to dealer right away, and they are saying it is normal. I even said E class brake system is away different from GLC 300 brake system and they are saying I cannot compare different class cars but have to compare same class cars. I think I have to compare GLC with different class of cars so that I could know the GLC has problem from manufacturing.

NHTSA ODI 11555404