There are 3 owner-reported electrical system complaints for the 2020 Mercedes-Benz C-Classin NHTSA's database. These are unverified consumer reports and may not reflect confirmed defects.
Car stops accelerating and shifts into neutral without warning I nearly got hit from behind. I have consulted several other Mercedes vehicle owners and all had the same issue. Two of the other owners stated that this happened on the interstate and was very lucky they were not involved in a collision. Both vehicles were GLC 300. Mercedes does not seem to have an answer to the issue and all previous owners traded vehicles for fear of dying.
points: ⸻ While driving, the vehicle displays the warning “Active Brake Assist Functions Limited – See Operator’s Manual.” The message appears during normal driving and does not go away. This warning indicates that the automatic emergency braking / Active Brake Assist system is limited or disabled, reducing a critical safety feature designed to help prevent or mitigate collisions. This creates a safety risk because the vehicle may not automatically brake in an emergency situation. The warning appeared suddenly while driving, with no visible obstructions, weather conditions, or damage to sensors. Restarting the vehicle does not consistently clear the message. The issue has not yet been inspected by a dealer or repair facility. The cause of the malfunction is UNKNOWN, and the vehicle is available for inspection.
The contact owns a 2020 Mercedes-Benz C300. The contact stated that her son was driving at an undisclosed speed when another vehicle's muffler detached and crashed into the undercarriage of the contact's vehicle. The front driver and passenger side tires exploded and fractured the rims. The contact stated that the vehicle's alert system failed to warn her son of the incoming object which resulted in the collision. The contact's son did not receive medical attention. A police report was filed. The vehicle was towed to the dealer and repaired. The manufacturer was made aware of the failure but provided no assistance. The failure mileage was 6,000.
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