2020 Mercedes-Benz C-Class Reliability Report

The most repeated complaint is the transmission dropping into neutral while driving or pulling away from a stop. The engine revs, the car does not move, and the driver has to shift to park or restart. Dealers often cannot reproduce it, and one replacement transmission did not cure it. C300 reports also cite a cylinder 2 failure from a worn exhaust valve seat and Camtronic camshaft solenoid faults that limit speed and then stall the car. Other filings cover engine harnesses corroded by camshaft sensor oil leaks, whining rear differentials, and start/stop that fails to restart.

Body parts come loose at speed. C-Class reports describe the roof panel between the windshield and sunroof peeling, rattling or flying off. That matches a recall, but some owners say their VIN was not included. Panoramic sunroofs shatter on the highway with a loud pop. Trim and fender flares detach from nearly new cars. Door hinges stop holding the door open, and one owner reports a leg injury. Much of the rest concerns the GLB rear spoiler recall, where parts were unavailable or VINs were excluded.

Sudden loss of steering control is the main concern, with four crash reports. Drivers describe steering that locks on the highway and a car that slid across lanes with lane assist on. Other reports mention grinding at low speeds, a wheel that resists or responds late, popping when turning, and a power steering-column adjustment stuck in place. C63 owners report wear on the inner edge of the tires within 5k to 9k miles. Several filings concern steering and suspension recall parts that were not available, mostly on GLB and A220 models.

The rear camera freezes, goes black after a few seconds, or shows a message saying it is not working. Two reports describe low-speed crashes while backing up. The rear emblem that houses the camera can stay open while the screen is dark. Failures show up from about 34,000 to 60,000 miles. Most filings concern the camera and MBUX screen recalls: parts unavailable, VINs left out, over-the-air updates that never arrived, or the problem coming back after the recall fix.

Airbag warning lights are the most common report, usually for the front passenger or left curtain airbag. The light often comes back days or weeks after a repair. A failed weight sensor in the passenger seat can leave that airbag disabled while the owner waits for a part with no delivery date. Four crash reports say airbags did not deploy in serious collisions, and seven injuries are logged. Other filings describe a pillar airbag going off with a bang while driving and airbag recalls still waiting for repair.

Panoramic sunroof glass shatters while driving, usually between 55 and 75 mph. Drivers hear a loud bang, and glass falls into the cabin. Three people report minor cuts from the shards, and in some cases the glass hit cars behind. Nothing warns of the failure first. Reports run from about 16,868 to 53,035 miles. Dealers usually quote a new sunroof, and the manufacturer told some owners the car is not under recall and offered no help.

Driver-assist systems act unpredictably. Reports describe hard automatic braking with nothing ahead, repeated at the same overpass shadow. Other drivers say the collision warning gave no alert before near-misses, or that adaptive cruise began braking too late after dealer service. Some get messages that all assist systems are inoperable, and dealers find no fault. One crash report describes the car losing power and stopping in a freeway lane, followed by a rear-end collision with injuries.