There are 1 owner-reported powertrain & transmission complaints for the 2021 Mercedes-Benz CLA-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
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.
Complaints are unverified consumer reports submitted to NHTSA. A high complaint count may reflect vehicle popularity, not defect severity. Data sourced from NHTSA public records.
Data synced from NHTSA on Apr 25, 2026