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.

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.

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.

My Mercedes Benz GLE450e Hybrid SUV has had a persistent but sporadic safety issue that suddenly causes the vehicle to go into "turtle mode" with a "performance extremely limited" warning when trying to accelerate quickly or sometimes when breaking quickly. In turtle mode, the car quickly loses acceleration, drops in speed and is then unable to accelerate properly. The sudden drop in speed and inability to accelerate causes a major safety issue while driving - particularly on roads with other vehicles also travelling at high speeds. Last Friday, I was driving with my family on Interstate 95 when a tractor trailer truck did not see me beside it and started to switch into my lane. I tried to quickly accelerate to get out of the way before it hit us but my car went into "turtle mode" and the speed suddenly dropped by 15 or 20mph and would no longer drive correctly. Luckily, I was in the right lane and able to swerve onto the shoulder of the highway and narrowly avoid the large truck. Otherwise, if I had been in a middle lane, I would have either been hit by the truck or likely hit another car next to me. This issue has been sporadically occurring with my car for about 5 months now. I have had it into the Mercedes dealer three times and, each time, they say they think they fixed the issue. But, each time the same issue has returned. They said that Mercedes USA knows it is a big issue with their new hybrid SUVs but Mercedes doesn't yet know how to fix the problem and has been unwilling to publicly acknowledge the problem or offer it's customers any assistance. Doing a quick Google search online for "Mercedes hybrid performance extremely limited" also quickly brings up different online forums where other owners of this same car have had the exact same issue that Mercedes has been unable to fix or resolve. Driving a car that can suddenly lose the ability to accelerate is a major safety hazard and I would sincerely appreciate if the NHTSA would help to address it

•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