2021 Mercedes-Benz GLC Reliability Report

Glass shatters with no impact. A rear window breaks while the car backs out slowly, and a sunroof bursts at highway speed. One fire report describes flames starting under the car on a short drive, with no warning, destroying the vehicle. Other complaints cover a moldy HVAC odor that persists after 4 dealer visits and causes headaches, and an unprotected front radiator that the owner links to a service campaign limited to 2019 models.

Fuel leaks are the most serious pattern. A high-pressure fuel line fails and gasoline pours from under the hood, in one case at about 1000 miles, and an incorrectly installed fuel line bracket leaves a large puddle of fuel and a car that will not start. Other reports describe power loss with a check engine light and a car stuck under 40 mph. One fuel pump failure is on a car the owner says is excluded from recall 23V880000.

Sunroof glass explodes outward with no prior impact, making a loud bang like a gunshot. In one case the closed fabric shade caught the fragments, which would otherwise have hit the occupants. Other complaints describe excessive frame rust that has needed repeated patches, and a front bumper on the coupe that leaves the radiator exposed to rock chips, which the dealer says it cannot address.

Repeated misfires, rough running, and hesitation come with a persistent check engine light, starting intermittently and getting worse until a dealer evaluation at about 65,000 miles. A separate pattern has the car suddenly refusing to go above 25 mph while driving 30 to 45 mph in city traffic, happening 3 times. The dealer says only a software update fixes it permanently, and that update is not yet available.

Stalling at about 35 mph in the rain leads to a cylinder head replacement at 19,369 miles in one report, and the failure returns after the repair. That owner links it to recall 23V445000, but the VIN is not covered. The other complaint is a parts delay. The 23V445000 recall repair cannot be done because the part is unavailable, though no failure has occurred.

Distronic cruise control reads Georgia's minimum speed 40 signs as speed limits and cuts speed abruptly from about 70 mph to 40 mph, a real hazard in heavy traffic. Turning off the automatic speed adjustment stops it. A separate report describes hesitation when pressing the accelerator, with no warning light, at about 7,000 miles. The dealer did not diagnose or repair it.