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Mercedes-Benz GLC 300Model year report

2021 Mercedes-Benz GLC 300 Problems

Compared with other Mercedes-Benz GLC 300 years

Typical for this model

52/100 1.0× a typical year · 50 = typical

Nearby years with fewer complaints than typical and no open NHTSA investigation: 2019

Based only on NHTSA complaints, recalls and investigations. Not adjusted for how many vehicles were sold, and not a reliability rating. How this is calculated

Complaints
67filed with NHTSA
Median mileage
26,000miles, 13 complaints with mileage
Recalls
9campaigns on record
Trend
RisingComplaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.
NHTSA crash rating
—no overall rating published
EPA fuel economy
25 mpgcombined, 2.0L 4-cyl RWD · 22 city / 29 hwy

Sources: NHTSA records for the 2021 Mercedes-Benz GLC 300 (complaints, recalls, investigations), EPA fuel economy. Report an error

What owners report

Owners of this model year most often describe engine trouble: a rough-running engine with the check engine light, misfires and a sudden drop in power, which dealers frequently traced to cylinder head work. A separate, well-represented group involves water getting into a headlamp and the light failing, and a smaller group reports reduced power traced to the fuel pump. Many complaints arrive at low mileage, though the headlamp reports tend to come later in the vehicle's life.

  1. Engine

    Cylinder head failure causing misfire and power loss

    • 20 complaints (30%)
    • median 35,000 mi at 1.9 yrs old (3 state mileage, few)
    • 1 mention a crash, fire or injury
    • owner-quoted repair $8,818 (median of 7 quotes)
    • filed 2021–2026

    Owners describe the check engine light coming on together with shaking, rough running and a sudden loss of power, sometimes limiting the car to low speed on a highway or incline. Several say the engine ran normally again after a restart, then the problem returned. According to the complaints, dealers first tried software updates and, in many cases, later diagnosed a leaking or failed cylinder head, quoting repairs in the thousands of dollars; some repairs were covered by warranty or goodwill and others were not. Reported from a few thousand miles up to roughly 67,000 miles, with many complaints logged between 30,000 and 60,000 miles.

    Recall 23V4450002 related service bulletins

    What to check: Ask for service records showing whether the check engine light has been addressed and whether any engine software update or cylinder head repair was done. On a test drive, watch for rough idle, hesitation or a stored check engine light.

    2 excerpts from owner complaints in NHTSA records

    “Twice my car slowed down tremendously in traffic because of a bad cylinder head. I drive a 2021 Mercedes GLC 300 4matic with 33,529 miles. In reviewing other complaints, this is a common and known complaint. My check engine light came on and I could not go over 40 mph. This is very dangerous.”

    NHTSA complaint #11696080, filed 2025-10

    “While driving in my neighborhood at 25 MPH, my Mercedes GLC300 suddenly lost power and the check engine light illuminated. My car would no longer exceed 25-30 MPH, but I drove it straight to the dealership and they said it was a faulty cylinder head and will cost $10,000 to fix! After intense negotiations, they agreed to fix it for $4,205.58, which was better, but still, that’s a lot to pay for a manufacturer’s defect! My car is a 2021 with only 67,540 miles on it.”

    NHTSA complaint #11739133, filed 2026-05
  2. Exterior lighting

    Moisture in headlight housing and lamp failure

    • 12 complaints (18%)
    • median 66,850 mi at 4.9 yrs old (2 state mileage, few)
    • filed 2024–2026

    Owners report condensation or water inside a headlamp housing, often noticed after rain, followed by the light dimming, flickering or stopping altogether. Several say a dealer attributed the damage to impact or told them the vehicle was not covered by the headlamp recall, and some were quoted the cost of a full headlamp assembly replacement. Complaints describe the moisture appearing without visible cracks in the lens. Mostly reported between roughly 40,000 and 95,000 miles, often after rain or a car wash.

    Recall 22V261000Recall 24V0700005 related service bulletins

    What to check: Inspect both headlamp housings for fogging, droplets or corrosion, and confirm both lights work on low and high beam. Ask whether the vehicle's VIN was included in the headlamp recall and whether any headlamp has already been replaced.

    2 excerpts from owner complaints in NHTSA records

    “The headlights stopped working due to water entering the assembly unit. First one side went out and then eventually the other side went out. The car was brought in to the dealership to fix and they stated it wasn’t covered. I’m recently learning about a recall of this issue with my type of car and I’m being told that my vehicle is not included in the recall.”

    NHTSA complaint #11682064, filed 2025-08

    “I seen a recall for certain 2021 GLC 300 vehicles for moisture in right side headlamp, causing headlamp to blow (go out). This happened on my 2021 GLC 300. Same moisture issue, same year, same model, however, my vin number does not show that it has a recall. I believe this safety issue needs to be expanded to include my vehicle. Same issue, same year, same make and same model”

    NHTSA complaint #11657172, filed 2025-04
  3. Fuel system

    Loss of power traced to the fuel pump

    • 12 complaints (18%)
    • median 28,000 mi at 3.0 yrs old (1 states mileage, few)
    • filed 2021–2026

    Owners describe the engine losing motive power at low speed or on an incline, with the check engine light on, and say a dealer or independent shop diagnosed a fuel pump fault. Some mention the fuel pump recall and state their vehicle was not included in it. A few describe a strong gasoline smell or fuel leaking under the hood, with a fuel line or bracket replaced. Reported across a wide range, from about 1,000 miles on a new vehicle up to around 28,000 miles.

    Recall 23V4450002 related service bulletins

    What to check: Ask whether the fuel pump recall repair has been completed and confirm it with the VIN. Check for fuel or gasoline smells around the engine bay and under the rear of the car, and ask for records of any fuel system repairs.

    2 excerpts from owner complaints in NHTSA records

    “Entered parked vehicle and noticed very strong gas fumes. Vehicle would not start. Looked under the vehicle and noticed very large quantity of gasoline on the ground. Vehicle was towed to Mercedes dealership in Rochester, Michigan. Diagnosis was an incorrectly installed fuel line bracket. New bracket was installed and problem was corrected.”

    NHTSA complaint #11421457, filed 2021-06

    “Fuel line malfunctioned, car stopped , gasoline was pouring out from under the hood. I was lucky that it did not catch fire, fire department showed up, closed the street, car was towed, dealership replaced high-pressure line of fuel system high pressure pump . It all started without a warning, suddenly after about 1 month of driving ( 1000 miles) a brand new Mercedes GLC300.”

    NHTSA complaint #11421117, filed 2021-06
  4. Electrical system

    Low battery warnings and electrical messages

    • 22 complaints (33%)
    • median 27,000 mi at 4.1 yrs old (6 state mileage, few)
    • 1 mention a crash, fire or injury
    • filed 2021–2026

    Owners report low battery alerts in the vehicle app or a message asking them to start the engine to charge the 12V battery, sometimes after short trips. Complaints describe being told to drive the car longer to recharge, and some mention infotainment displays that stay black or reboot. Others describe driver-assist warnings such as blind spot or active brake assist messages appearing on the dash. Reported at varied mileage, often on vehicles used for short trips or infrequently.

    Recall 21V354000Recall 22V365000Recall 21V0580004 related service bulletins

    What to check: Check that the 12V battery holds charge, ask whether the latest infotainment and communication module software updates were applied, and test the driver-assist systems on a test drive.

    2 excerpts from owner complaints in NHTSA records

    “Vehicle will flash warnings on dash the the blind spot assist in inoperative and the front passenger air bag malfunction. The active brake assist is also malfunctioning as the two white cars colliding is on. The dealership as tried to fix this issue 5 times and has tried argue the the active brake assist is functioning normal.”

    NHTSA complaint #11499353, filed 2022-12

    “Mercedes App displays low battery alert. Brought to dealer who stated Mercedes told them (dealer) to inform anyone coming in with this issue to just disregard the alert in the app. Had the battery checked anyway. At the conclusion was told I had to “drive the car longer so the battery would recharge”.”

    NHTSA complaint #11632268, filed 2024-12

Buying note. Ask for a full service history and check the VIN against open recalls before purchase, since engine work and headlamp moisture are the two areas owners write about most. A pre-purchase inspection by a shop familiar with the model, including a fault-code scan and a headlamp check, is worthwhile.

Summary written with AI from a sample of 60 NHTSA complaints for this model year (picked at random, with complaints that state a mileage and recent ones taken first), then checked automatically against the source records. Where a problem shows a complaint count, every complaint for this model year was matched with fixed keyword rules (written with AI and tested against the sample), and the mileage, age and repair figures are calculated from those complaints; owners' figures are as stated, not verified. Other counts refer to the sample. The excerpts come from NHTSA's public complaint records and are unverified; capitalisation is normalised, NHTSA staff notes are removed, and shortened text ends with “…”. Something wrong? Request a correction.

NHTSA recorded 67 consumer complaints for the 2021 Mercedes-Benz GLC 300. 13 of the complaints include a mileage, and 77% of those were filed for vehicles with under 50,000 miles; the median is 26,000 miles. Of all complaints, 2 involved a crash, 2 a fire, 1 an injury, according to the filers. NHTSA lists 9 recall campaigns and 218 technical service bulletins for this model year. Compared with the other 7 Mercedes-Benz GLC 300 model years that have at least 25 complaints and are old enough to compare, this one scores 52 out of 100, where 50 is a typical year for the model (typical for this model). The comparison allows for the era and for how long each year has had to collect complaints, but not for how many vehicles were sold.

Which parts are reported most

Complaints can name more than one part, so the counts add up to more than the total. Select a part to see its complaints, recalls and bulletins.

Also reported: Lane departure (2), Vehicle speed control (2), Air bags (1).

Example complaints

Engine: “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 complaint #11399796, filed 2021-03, 10 miles

Exterior lighting: “I own a 2021 Mercedes-Benz GLC 300. The vehicle developed moisture/condensation in the headlamp, and the affected headlamp subsequently failed. I took the vehicle to RBM of Alpharetta, an authorized Mercedes-Benz dealership. I was advised that corrosion was found in the affected headlamp and that the headlamp assembly requires replacement. On September 8, 2026, the dealership provided a repair estimate of $3,387.33. The vehicle had approximately 84,769 miles. …”

NHTSA complaint #11763616, filed 2026-09

Fuel 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. …”

NHTSA complaint #11413885, filed 2021-04, 90 miles

Electrical system: “Have been getting condensate inside vehicle headlights inwhich have cause the headlight to completely not work anymore.. There is no damage to headlight which means to be cause due to a problem with the seal. Checked with local and also statewide Mercedes advisors which was told there isn’t a recall for my vehicle inwhich I looked online and found an recall for vehicles just like the one I have.. Recall number 22V261000-Recall Date 04-14-2022. I’m asking for my vehicle to be inspected and repaired free of charge . …”

NHTSA complaint #11674539, filed 2025-07

Mileage when problems were reported

77% of the 13 complaints with a mileage were filed for vehicles with under 50,000 miles; the middle half falls between 7,000 and 41,000 miles.

31%0–108%10–2538%25–508%50–7515%75–1000%100–1500%150+
Share of complaints by mileage when the problem was reported, in thousands of miles (13 complaints with mileage). Red bars: under 50,000 miles. Bucket widths differ. Median: 26,000 miles.

Complaints by year filed

Trend: rising. Complaints filed in the last 3 full calendar years are at least 25% higher than in the 3 years before.

20212022202320242025182026
Complaints by year the complaint was filed with NHTSA. Red bars: the last 3 full calendar years used for the trend. The current year (2026) is partial.

Fuel economy and running cost

EPA ratings for each 2021 Mercedes-Benz GLC 300 version. Annual fuel cost is the EPA's estimate at its current fuel prices for 15,000 miles a year (55% city driving).

VersionEngineTransmissionCityHwyComb.Fuel / yr
GLC300 RWD2.0L 4-cyl9-speed automatic222925$3,300
GLC300 4matic 4WD2.0L 4-cyl9-speed automatic212823$3,550
GLC300 4matic Coupe 4WD2.0L 4-cyl9-speed automatic222824$3,400

Source: U.S. EPA and Department of Energy, fueleconomy.gov. Ratings are for comparing vehicles; real-world mileage varies with driving and conditions.

Recalls and investigations

See all 9 recalls for the 2021 Mercedes-Benz GLC 300 → · Check a VIN at nhtsa.gov/recalls

Technical service bulletins

TSBs are manufacturer notes to dealers about known repair procedures. They are not recalls and do not by themselves mean a vehicle has a fault. 218 on record; the latest 10 are shown.

See all 218 bulletins →

Other model years of the Mercedes-Benz GLC 300

YearComplaintsMedian miRecallsCrash ★MPGScore (50 = typical)Trend
2025164,7003—27—Too new
2024212,1748—29—Too new
2023558,50012—2867 · MoreToo new
20226110,000252439 · TypicalRising
20216726,0009—2552 · TypicalRising
20207021,25016—2454 · TypicalRising
20194741,500125240 · FewerRising
20188710,5001252448 · TypicalRising
201710129,41612—2445 · TypicalRising
201613411,00012—2480 · MoreFalling

All Mercedes-Benz GLC 300 model years · Best and worst years by complaints

Frequently asked questions

What are the most common problems with the 2021 Mercedes-Benz GLC 300?

Owners of this model year most often describe engine trouble: a rough-running engine with the check engine light, misfires and a sudden drop in power, which dealers frequently traced to cylinder head work. The issues reported most often: Cylinder head failure causing misfire and power loss; Moisture in headlight housing and lamp failure; Loss of power traced to the fuel pump.

How many NHTSA complaints does the 2021 Mercedes-Benz GLC 300 have?

NHTSA recorded 67 consumer complaints for the 2021 Mercedes-Benz GLC 300 as of Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.

What part of the 2021 Mercedes-Benz GLC 300 is reported most often?

Engine is named most often, in 30 complaints (45% of the total), followed by exterior lighting with 13.

Has the 2021 Mercedes-Benz GLC 300 been recalled?

NHTSA lists 9 recall campaigns for this model year. To check a specific vehicle, enter its VIN at nhtsa.gov/recalls.

What gas mileage does the 2021 Mercedes-Benz GLC 300 get?

The EPA rates the 2021 Mercedes-Benz GLC 300 (GLC300, 2.0L 4-cyl) at 25 mpg combined, 22 city and 29 highway, with an estimated annual fuel cost of $3,300 at 15,000 miles a year. Other engine and drive versions are rated differently.

At what mileage are problems with the 2021 Mercedes-Benz GLC 300 reported?

Among the 13 complaints that include a mileage, the median is 26,000 miles and the middle half falls between 7,000 and 41,000 miles; 77% were filed for vehicles with under 50,000 miles.

About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 31, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate. Fuel economy is from the EPA and DOE (fueleconomy.gov).

Complaint counts come from NHTSA’s public complaint database; we count each complaint once. The source records for this vehicle are on nhtsa.gov. Scores and trends are our own summaries of that data, described in the methodology. This page is not legal, safety or repair advice: for a specific vehicle, check its VIN at nhtsa.gov/recalls and ask a qualified mechanic. See an error? Tell us.