2020 Mercedes-Benz GLC Reliability Report

Reports here are scattered rather than one dominant fault. The power steering column adjustment can stop working and leave the wheel stuck in an awkward position. Some owners describe steering wheel and seat vibration from new, which dealers blame on tires, and front tires wearing heavily on the outer edge, replaced several times without a fix. Others report a persistent squeak from the suspension. With the Distronic driver assistance system on, the car can wander within the lane on gentle highway curves and drift toward lane markings unless the driver steers.

The rearview camera shows a blank screen or a mirror-reversed image when the car is put in reverse, often right after startup. Owners link these failures to two federal recall campaigns, but some find their VIN is not included. Others say the fix for the infotainment system, which can stay black or reboot and drop the camera image, was promised over the air and still had not arrived more than a year later. One dealer quoted $6000 to repair a screen that would not come on.

Water gets inside the headlight housing, often after rain, and condensation builds until the whole assembly fails. When it goes, the headlight, turn signal, and parking light on that side all stop working, sometimes with no prior warning. Failures appear around 65,000 miles, and one owner reports the problem returned after a warranty replacement. Replacement is costly, quoted at over $2500 from independent shops and over $3300 from dealers. The loss of a turn signal and night lighting is the main safety concern.

Unexpected braking and power loss are the main concerns. One report describes a total loss of power on a freeway with no warning, leading to a rear-end crash with 3 injuries. Another describes hard automatic braking at about 35 mph under the shadow of an overpass, repeated at the same spot. The radar cruise control is reported to brake too late in stop-and-go traffic after a dealer service visit. A separate complaint involves an airbag system warning caused by a faulty right-side crash sensor.

Hesitation and power loss at low speed lead the complaints. Owners describe the car failing to respond to the throttle for up to 4-5 seconds when pulling into traffic or making a sharp turn, and in some cases acting as if it slipped into neutral until restarted. One GLC63 report describes a transmission overheat warning and the car locking in first gear at highway speed. A whining rear differential needing replacement around 61,198 miles is also reported, at a cost near $9,088.

After stopping, often while waiting to turn, the car refuses to accelerate beyond a crawl even with the pedal pressed, leaving the driver stuck in an intersection or in front of traffic. Turning the car off and on usually restores power. One report, at approximately 800 miles, was traced to electronic throttle control software that the dealer could not replace. Dealers often cannot reproduce the fault. Owners describe near misses with oncoming traffic and trucks.

Only two complaints, but both are serious. In one crash at 40 mph, the driver airbag did not deploy while the passenger airbag did, and an injury followed. The other describes an airbag warning light that stays on and indicates the front passenger seat airbag is not working, at approximately 30,000 miles, with no cause found and no help from the dealer or manufacturer.