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What 61 owners told NHTSA about the 2021 Mercedes-benz GLC Coupe

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 (61)Crash / fire / injury (2)Engine (29)Fuel system (11)Lights (10)Electrical system (7)Visibility & wipers (4)Backup camera & sensors (3)Body & structure (3)Driver assistance (3)Transmission & drivetrain (3)Speed control (2)

29 of 61 complaints match · Engine · clear filters · page 2 of 2

Sep 3, 2021Speed controlEngine

The contact owns a 2021 Mercedes-Benz GLC300. The contact stated while driving at various speeds, the vehicle hesitated to accelerate while the accelerator pedal was depressed. The contact stated there was no warning light illuminated. The vehicle was taken to a local dealer but was not diagnosed or repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 7,000.

NHTSA ODI 11431621

Apr 26, 2021EngineFuel system

ON APRIL 21, 2021 AT ABOUT 1800 (TIME), LESS THAN 45-HOURS AFTER PURCHASE OF THE NEW 2021 GLC 300 VEHICLE, THE INTERNAL COMBUSTION (ENGINE) MISFIRED AND ABRUPTLY MALFUNCTIONED WHILE IN STEADY ACCELERATION AT 65-MPH. MY FAMILY AND I WERE HEADED EASTBOUND ON THE CA-60 FREEWAY IN LANE THREE (LEFTMOST, FASTEST LANE). AS SOON AS THE ENGINE SPONTANEOUSLY SPUTTERED, IT ABRUPTLY STOPPED AND INTENSELY SHOOK THE ENTIRE CAR VIGOROUSLY, AGGRESSIVELY, AND CONTINUOUSLY WITH NO ABILITY FOR CONTROL NOR FOR THE OPTION TO CONTINUE TO ACCELERATE. THERE WERE THREE CARS BEHIND MY VEHICLE ALSO ACCELERATING AT THE SPEED OF TRAFFIC (65-MPH) THAT ALSO ABRUPTLY SCREECHED TO A HALT TO STEER CLEAR OF MY UNUSUALLY MALFUNCTIONING VEHICLE. THIS WAS THE MOST TRAUMATIC EVENT THAT HAS EVER HAPPENED TO MYSELF AND MY FAMILY IN OUR LIFETIME. AS YOU CAN IMAGINE, WE FEEL EXTREMELY FORTUNATE IN HAVING SURVIVED THIS HORRENDOUS, UNEXPECTED, AND CRUEL SAFETY RISK AS NO COLLISION WAS FORTUNATELY REPORTABLE. THE VEHICLE'S MALFUNCTIONING AND PERFORMANCE ISSUE HAD PLACED US IN AN EXTREMELY HIGH-RISK OF SAFETY CONCERNS AND NEAR MOMENTS FROM MY OR MY FAMILY'S HEALTH-RELATED TRAGEDY AS THE HALT OF NUMEROUS CARS WITHIN THE FREEWAY CLOSELY SWERVED-AWAY FROM OUR DIRECTION. AS YOU CAN IMAGINE, WE ARE SEVERELY, PHYSICALLY, EMOTIONALLY, AND MENTALLY DISTRAUGHT DUE TO THE MANUFACTURING DEFECT TO THE 2021 GLC 300 ENGINE. AFTER 30-HOURS OF CONTINUED QUESTIONING, ANALYSIS AND DISCOVERY, IT WAS CONFIRMED OF VALVE TRAIN COMPONENT DEFECT CAUSING MAJOR DOWNSTREAM EFFECTS TO THE ENGINE AND IMMEDIATE INABILITY TO ACCELERATE ON THE HIGHWAY WITH DIRECT SERIOUS LIFE THREATENING RISK TO A NEW VEHICLE AND MY FAMILY WITHIN IT. PLEASE CONSIDER THIS DETRIMENTAL INCIDENT FOR OTHER'S GLOBAL SAFETY THROUGH MY TRAGIC EXPERIENCE.

NHTSA ODI 11413885

Mar 29, 2021Engine

2021 MERCEDES GLC. CONSUMER WRITES IN REGARDS TO VALVE SPRING FAILURE AND STALLED ENGINE. *LD THE CONSUMER STATED SHORTLY AFTER PURCHASING THE VEHICLE, THE VALVE SPRING BROKE CAUSING THE ENGINE TO FAIL WHILE DRIVING. THE FAILURE MILEAGE WAS 199. THE CONSUMER STATED THE ROADSIDE ASSISTANCE GROSSLY UNDER ESTIMATED IT'S ARRIVAL TIME. ALSO, THE CONSUMER WAS IN AN UNFAMILIAR AREA BUT, ROADSIDE ASSISTANCE REQUIRED AN ADDRESS BEFORE SENDING THE TOW TRUCK. THE CONSUMER HAD TO WALK THE STREET TO FIND AN ADDRESS ON A HOME. THE CONSUMER FELT THE DEALERSHIP ATTEMPTED TO DOWNPLAY THE FAILURE AS A SIMPLE FIX. THE MANUFACTURER WAS NOTIFIED AND OFFERED GOODWILL ASSISTANCE WHICH THE CONSUMER ACCEPTED. *JS *JS

NHTSA ODI 11404535

Mar 8, 2021Body & structureEngine

I HAVE PURCHASED THE 2021 MERCEDES-BENZ GLC 300 4MATIC COUPE AND NOTICED A DESIGN FLAW ON THE CAR. AS YOU CAN SEE IN THE ATTACHED PICTURE, THE FRONT BUMPER PROVIDES NO PROTECTION TO THE RADIATOR. IT HAS ALREADY STARTED CHIPPING DUE TO THE ROCK DAMAGE. THIS CAN LEAVE THE CAR IMPAIRED ON THE FREEWAY WHICH CAN BE DANGEROUS. I DID CONTACT THE DEALER AND THEY SAID THERE IS NOTHING THEY CAN DO.

NHTSA ODI 11399796

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Working with the data? Download all 61 complaints as CSV · fetched from NHTSA July 20, 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 GLC Coupe verdict →