2021 Mercedes-Benz C300 Problems
- Complaints
- 14filed with NHTSA
- Median mileage
- 86,078miles, 3 complaints with mileage
- Recalls
- 7campaigns on record
- Trend
- Not enough dataFewer than 15 complaints, too few for a reliable trend.
- NHTSA crash rating
- 5 / 5stars overall, 2 rated versions
- EPA fuel economy
- 27 mpgcombined, 2.0L 4-cyl RWD · 23 city / 35 hwy
Sources: NHTSA records for the 2021 Mercedes-Benz C300 (complaints, recalls, investigations), NHTSA crash tests, EPA fuel economy. Report an error
NHTSA recorded 14 consumer complaints for the 2021 Mercedes-Benz C300. The part named most often is engine, with 8 complaints (57% of the total), followed by fuel system (3) and air bags (1). 3 of the complaints include a mileage, and 0% of those were filed for vehicles with under 50,000 miles; the median is 86,078 miles. NHTSA lists 7 recall campaigns and 178 technical service bulletins for this model year. Engine complaints overlap with 11 technical service bulletins filed under the same part. Fuel system complaints overlap with 1 recall campaign covering the fuel pump and 7 technical service bulletins filed under the same part.
This model year has fewer than 25 complaints on record, so the numbers below can change a lot with a few new reports.
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.
- Engine8 57%
- Fuel system3 21%
- Air bags1 7.1%
- Electrical system1 7.1%
Example complaints
Engine: “My C300 only had about 42,000 miles and was less than 5 years old. Just after the factory warranty expired, the engine was running rough and hot, and check engine light illuminated. My local garage quickly diagnosed the problem as a failed cylinder head, stated that it is common with Mercedes 4-cylinder engines from about 2017, and said Mercedes may cover it since it is a known problem and shouldn't happen with that mileage. …”
NHTSA complaint #11678865, filed 2025-08Fuel system: “My car had a coolant leak last year a hose broke and I have a 2021. My son’s mercedes sis the same thing on 11/23/2025. I have researched ma y others with this same issue. There should be a recall on that hose or whatever the problem Is.”
NHTSA complaint #11701496, filed 2025-11Air bags: “The contact owns a 2021 Mercedes-Benz C300. The contact stated while driving at an unknown speed, there was a burning odor inside the vehicle. The contact stated the passenger side air bags was enabled warning light was illuminated. The contact also stated the vehicle made an abnormal noise. The contact took the vehicle to the local dealer but was unable to duplicate the failure. The manufacturer had not been informed of the failure. The failure mileage was unknown.”
NHTSA complaint #11453645, filed 2022-02Mileage when problems were reported
0% of the 3 complaints with a mileage were filed for vehicles with under 50,000 miles; the middle half falls between 60,000 and 88,000 miles.
Complaints by year filed
Fewer than 15 complaints, too few for a reliable trend.
Crash test ratings
NHTSA's 5-Star Safety Ratings for the 2021 Mercedes-Benz C300. Frontal results are shown driver / passenger; rollover shows the star rating and NHTSA's estimated risk of rolling over in a single-vehicle crash.
| Version | Overall | Frontal | Side | Side pole | Rollover |
|---|---|---|---|---|---|
| C-Class · sedan 4WD | ★★★★★ | 5 / 4 | 5 | 5 | 4 · 11.1% risk |
| C-Class · sedan RWD | ★★★★★ | 5 / 4 | 5 | 5 | 4 · 11.1% risk |
Source: NHTSA New Car Assessment Program (5-Star Safety Ratings), nhtsa.gov/ratings.
Fuel economy and running cost
EPA ratings for each 2021 Mercedes-Benz C300 version. Annual fuel cost is the EPA's estimate at its current fuel prices for 15,000 miles a year (55% city driving).
| Version | Engine | Transmission | City | Hwy | Comb. | Fuel / yr |
|---|---|---|---|---|---|---|
| C300 RWD | 2.0L 4-cyl | 9-speed automatic | 23 | 35 | 27 | $3,050 |
| C300 Convertible RWD | 2.0L 4-cyl | 9-speed automatic | 23 | 31 | 26 | $3,150 |
| C300 Coupe RWD | 2.0L 4-cyl | 9-speed automatic | 24 | 33 | 27 | $3,050 |
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
- 23V445000Jun 26, 2023Fuel system, gasoline › Delivery › Fuel pumpCovers: Mercedes-Benz C300 2021–2023, GLC 300 2021–2023, AMG G63 2021–2023 +37 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021-2023 C-Class, E-Class, S-Class, CLS, SL, GT, GLC, GLE, GLS, and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle details. The fuel pump may shutdown, which can result in a…
- 22V365000May 20, 2022Communication › Auto crash notificationCovers: Mercedes-Benz C300 2017–2021, GLS 450 2017–2021, GLA 250 2017–2021 +48 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2017-2022 CLA-Class, GLA-Class, GLE-Class, GLS-Class, SLC-Class, A-Class, AMG GT-Class, C-Class, E-Class, S-Class, SL-Class, GLC-Class, CLS-Class, GLB-Class, and G-Class vehicles. Please refer to MBUSA's…
- 22V232000Apr 8, 2022Back over prevention › Display functionCovers: Mercedes-Benz C300 2019–2021, E 450 2019–2021, AMG C43 2019–2021 +27 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2018-2021 CLA-Class, GLE/GLS-Class, A-Class, C-Class, E-Class, E-Class Coupe/Convertible, GLA/GLB-Class, GLC-Class, and CLS-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model…
- 21V406000May 28, 2021Seats › Mid/rear assembly › Head restraintCovers: Mercedes-Benz C300 2021, AMG E53 2021, E 450 2021 +3 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 C300 Cabriolet, C43 AMG Cabriolet, C63 AMG Cabriolet, C63 AMG S Cabriolet, E450 Cabriolet, and E53 AMG Cabriolet vehicles. The rear headrests may be incorrectly mounted to the seatbacks.
- 21V230000Apr 1, 2021SeatsCovers: Mercedes-Benz C300 2021, AMG E53 2021, GLC 300 2021 +15 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2021 C-Class, E-Class, E-Class Coupe and Convertible, GLC, CLS, AMG GT 4-door Coupe and G-Class vehicles. Please refer to MBUSA's recall report for specific vehicle model details. A faulty electrical…
- 21V058000Feb 5, 2021Communication › Auto crash notificationCovers: Mercedes-Benz C300 2016–2021, CLA250 2016–2021, GLC 300 2016–2021 +65 more
Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2016 - 2021 CLA-Class, GLA-Class, GLE-Class, GLS-Class, SLC-Class, A-Class, GT-Class, C-Class, E-Class, S-Class, CLS-Class, SL-Class, B-Class, GLB-Class, GLC-Class, and G-Class vehicles. Please refer to the…
See all 7 recalls for the 2021 Mercedes-Benz C300 → · 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. 178 on record; the latest 10 are shown.
- 11038188Sep 26, 2026Steering. Complaint Slight creaking noises when steering. Cause Noises may come from one or more sleeves of the horn contact plate. Remedy Remove the horn contact plate and check the sleeves for noise; see…
- 11038187Sep 26, 2026Transmission and drivetrain. Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic /9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For…
- 11038186Sep 22, 2026Brakes. Complaint Repeat workshop visit for vehicle vibration while braking from 60MPH. NOTE: Although the symptom is similar to a tire or wheel vibration, it is usually readily noticeable that it is…
- 11038217Sep 14, 2026Body and structure. Complaint Clanking noise from the area of the speakers in the doors. Cause Under analysis. Remedy To narrow down the cause, first of all remove the door trim. • If the noise continues to occur even…
- 11037987Sep 14, 2026Transmission and drivetrain. Complaint Only vehicles with a variable transfer case are affected. This can be identified through control unit N45 or N15/7 in the quick test. When accelerating with light load, vibrations or…
- 11037616Sep 4, 2026Transmission and drivetrain. Complaint Customer complaints relating to automatic transmission 725.0 (NAG3 Classic / 9G‑TRONIC automatic transmission) and 725.1 (NAG3 facelift/9G‑TRONIC automatic transmission facelift) For…
- 11037228Aug 28, 2026Steering. Complaint During part of the steering movement, it feels heavier or more difficult to steer in the same spot every time. OR Rattling, humming, dry sliding/gravel noise from the electric steering…
- 11036516Aug 26, 2026Transmission and drivetrain. Complaint • Harsh 1‑2, 2‑3, and/or 3‑4 shift • Jerky shifting • Jolting when accelerating from stop Cause Insufficient software application causing elevated K81/K27/B05 fill time adaptations and…
- 11036511Aug 24, 2026Electrical system, Body and structure. Complaint Tailgate opens unintentionally. Cause Accidental or unnoticed activation of the button to open the tailgate on the vehicle key. EXAMPLE: when stored in trouser pocket, handbag etc. Remedy…
- 11036999Aug 15, 2026Fuel system. Dear Mercedes-Benz Owner: In our continuing efforts to ensure the proper performance of Mercedes-Benz products and to enhance the satisfaction of our customers, Mercedes-Benz USA is extending the…
Other model years of the Mercedes-Benz C300
| Year | Complaints | Median mi | Recalls | Crash ★ | MPG | Score (50 = typical) | Trend |
|---|---|---|---|---|---|---|---|
| 2024 | 11 | — | 3 | — | 30 | — | Too new |
| 2023 | 22 | 3,900 | 9 | — | 25 | — | Too new |
| 2022 | 25 | 6,000 | 9 | — | 25 | 33 · Fewer | Rising |
| 2021 | 14 | 86,078 | 7 | 5 | 27 | — | Not enough data |
| 2020 | 33 | 28,722 | 9 | — | 25 | 42 · Typical | Stable |
| 2019 | 69 | 22,626 | 17 | — | 25 | 47 · Typical | Rising |
| 2018 | 99 | 50,000 | 18 | 5 | 25 | 38 · Typical | Rising |
| 2017 | 216 | 28,000 | 15 | 5 | 26 | 77 · More | Rising |
| 2016 | 291 | 40,300 | 13 | 5 | 28 | 72 · More | Rising |
| 2015 | 381 | 48,500 | 11 | 4 | 28 | 86 · More | Stable |
| 2014 | 94 | 27,000 | 5 | 5 | 22 | 13 · Fewer | Stable |
| 2013 | 262 | 80,000 | 6 | 5 | 22 | 39 · Typical | Falling |
| 2012 | 267 | 83,500 | 6 | — | 20 | 28 · Fewer | Falling |
| 2011 | 480 | 79,000 | 6 | 4 | 21 | 53 · Typical | Falling |
| 2010 | 453 | 65,300 | 6 | — | 21 | 66 · More | Falling |
| 2009 | 576 | 70,000 | 8 | — | 21 | 84 · More | Falling |
| 2008 | 672 | 78,890 | 7 | — | 21 | 69 · More | Stable |
All Mercedes-Benz C300 model years · Best and worst years by complaints
Frequently asked questions
How many NHTSA complaints does the 2021 Mercedes-Benz C300 have?
NHTSA recorded 14 consumer complaints for the 2021 Mercedes-Benz C300 as of Oct 30, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate.
What part of the 2021 Mercedes-Benz C300 is reported most often?
Engine is named most often, in 8 complaints (57% of the total), followed by fuel system with 3.
Has the 2021 Mercedes-Benz C300 been recalled?
NHTSA lists 7 recall campaigns for this model year. To check a specific vehicle, enter its VIN at nhtsa.gov/recalls.
How did the 2021 Mercedes-Benz C300 do in NHTSA crash tests?
NHTSA's 5-Star Safety Ratings give the 2021 Mercedes-Benz C300 5 out of 5 stars overall, across 2 rated versions (body style and drive). Ratings from different model years are only comparable when the vehicle was not redesigned in between.
What gas mileage does the 2021 Mercedes-Benz C300 get?
The EPA rates the 2021 Mercedes-Benz C300 (C300, 2.0L 4-cyl) at 27 mpg combined, 23 city and 35 highway, with an estimated annual fuel cost of $3,050 at 15,000 miles a year. Other engine and drive versions are rated differently.
At what mileage are problems with the 2021 Mercedes-Benz C300 reported?
Among the 3 complaints that include a mileage, the median is 86,078 miles and the middle half falls between 60,000 and 88,000 miles; 0% were filed for vehicles with under 50,000 miles.
About this data. Data from NHTSA (ODI) complaints, recalls, TSBs and investigations, updated Oct 30, 2026. Complaints are unverified consumer reports and may be duplicated or inaccurate. Crash ratings are from NHTSA’s New Car Assessment Program. 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.