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What 5 owners told NHTSA about the 2021 Mercedes-benz CLA

These are the actual owner complaints behind this car’s reliability verdict, filed with the federal government, unedited. They’re unverified reports, not confirmed defects: read them as leads for your pre-purchase inspection, not a diagnosis.

All (5)Crash / fire / injury (2)Speed control (2)Engine (1)Fuel system (1)Lights (1)Suspension (1)Transmission & drivetrain (1)

2 of 5 complaints match · Speed control · clear filters

Jun 17, 2024Transmission & drivetrainSpeed controlEngine

Our car has lost power to accelerate on 4 occasions on the highway. The first instance was in October of 2023, the second instance was in November of 2024 (and was brought immediately to the dealership and they said the fix wasn't available yet), the third instance was in March of 2024 and the most recent incident occurred in June of 2024. For example, the car will be moving at a speed of 60 mph and it will suddenly start flashing lights in the car with a warning signal that the "car is unable to reserve". The car then instantly loses the ability to accelerate and you can push the pedal all the way down and it will not go faster. There is an issue with either the engine, the power train or the speed control, or some combination. The car will not go above 20 miles per hours. These instances have almost caused us to get rear-ended by other vehicles as we suddenly lose the ability to accelerate. It is extremely dangerous and we've been fortunate to be near off-ramps to get off. The problem has been confirmed by Mercedes Dealerships with friends of ours who have experienced the same problem with a different model. They claimed that Mercedes USA had not found a fix yet, but refused to provide us with a loaner car until this death trap of a car was fixed.

NHTSA ODI 11594916

Mar 5, 2024Speed controlFuel system

Date of occurrence: 03/05/2024 Subject: Formal Claim Regarding Traffic Safety Issue with 2021 Mercedes Benz CLA 250 I am writing to formally submit a claim regarding a recent traffic safety incident involving my 2021 Mercedes Benz CLA 250. While driving to my destination, I encountered a sudden loss of power and inability to accelerate. To ensure the safety of myself and other drivers, I activated my emergency lights and cautiously proceeded at a limited speed of approximately 30 mph, accompanied by a strained engine sound. Understanding the potential risks associated with this issue, I immediately pulled over in a safe location and had to drive the vehicle with caution to my home where I then arranged for my vehicle to be towed to the service department. Upon inspection, the service department informed me that the problem stemmed from a software malfunction, for which Mercedes has not yet released an updated version. Given the nature of this incident and the potential safety hazards it poses, I am deeply concerned about the safety of driving my vehicle on the freeway or to any destination. I kindly request your assistance in addressing this matter promptly and ensuring the necessary steps are taken to rectify the software malfunction. Please let me know the next steps in the claims process, any additional documentation or information required, and the estimated timeline for resolution. I appreciate your attention to this matter and look forward to a swift resolution. Thank you.

NHTSA ODI 11575656

Working with the data? Download all 5 complaints as CSV · fetched from NHTSA July 19, 2026

How to use these: a complaint is one owner’s report, filed voluntarily and published unverified. Patterns matter more than any single story. If several owners describe the same failure at similar mileage, put that system at the top of your pre-purchase inspection list. Back to the full 2021 Mercedes-benz CLA verdict →