Mercedes-Benz C300 4matic Convertible
What it costs to keep fuelled
$1,920a year, fuel only
The 2023 Mercedes-Benz C300 4matic Convertible is EPA-rated at 25 MPG combined (21 city / 30 highway). Over 15,000 miles a year that is about 600 gallons, $1920 a year in fuel, or $0.128 per mile at $3.20/gal.
Across its full 2017–2023 run it averages 24.6 MPG, essentially flat across 7 model years.
The band is how far one gallon carries it: 25 of the 60 MPG this scale runs to. The square tick is the subcompact cars average, 24.2.
- Fuel, per year
- $1,920 at 15,000 mi
- Per mile
- $0.128
- Per kilometre
- $0.080
- Gallons burned/yr
- 600
1 mile = 1.609344 km · fuel at $3.20/gal, fixed JUL 2026
Test figure — not a road resultSOURCE·US EPA fuel-economy test data·FUEL ASSUMED AT $3.20/GAL FROM JUL 2026·REVIEWED JUL 2026
How this is worked out
- Start from the EPA combined figure for the model year — a laboratory test cycle run to a fixed procedure, not a road result. Where a year sold several engines or drivetrains, the trims are averaged and the trim count is printed beside the row so you can see how much averaging is behind it.
- Fix a pump price. This site keeps one reference price, $3.20 a US gallon, fixed JUL 2026 and printed next to every dollar figure it produces. It is an assumption with a date on it, not a quote — put your own price in.
- Fix an annual distance. Every annual figure on this site uses 15,000 miles a year, roughly the US average. A cost per year with no stated distance is not a number, it is a mood.
- Divide distance by economy for gallons, multiply by price for the year's fuel, divide price by economy for one mile. The per-kilometre line is that last figure divided by 1.609344 — the same money, in the unit most of the world drives in.
- Stop there. No depreciation, no tyres, no insurance, no servicing. This is the fuel line of the ledger and it is labelled as one; depreciation usually dwarfs everything on it.
gallons/yr = miles/yr ÷ MPG fuel $/yr = gallons/yr × $/gal cost $/mi = $/gal ÷ MPG cost $/km = cost $/mi ÷ 1.609344
The full method, the licence note, and what a test figure cannot tell you →
Re-run the ledger at another pump price
Every line above rests on one pump price. Here is the same entry re-costed at six others, because the price is the part that changes while the test sheet stays put.
| Fuel price | Per mile | 10,000 mi/yr | 15,000 mi/yr | 20,000 mi/yr |
|---|---|---|---|---|
| $2.50/gal | $0.100 | $1000 | $1500 | $2000 |
| $3.00/gal | $0.120 | $1200 | $1800 | $2400 |
| $3.20/gal | $0.128 | $1280 | $1920 | $2560 |
| $3.50/gal | $0.140 | $1400 | $2100 | $2800 |
| $4.00/gal | $0.160 | $1600 | $2400 | $3200 |
| $4.50/gal | $0.180 | $1800 | $2700 | $3600 |
| $5.00/gal | $0.200 | $2000 | $3000 | $4000 |
SOURCE·US EPA fuel-economy test data·FUEL ASSUMED AT $3.20/GAL FROM JUL 2026·REVIEWED JUL 2026
The whole service history, sheet by sheet
7 model years on file. Read down the combined column: a nameplate that got heavier shows it here long before any brochure admits it.
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 2023 | 25 MPG | 21 | 30 | $3100 | 358 | 1 |
| 2022 | 24 MPG | 21 | 30 | $3200 | 361 | 1 |
| 2021 | 25 MPG | 22 | 30 | $3100 | 359 | 1 |
| 2020 | 24 MPG | 21 | 29 | $3200 | 374 | 1 |
| 2019 | 24 MPG | 21 | 29 | $3200 | 372 | 1 |
| 2018 | 25 MPG | 22 | 29 | $3100 | 360 | 1 |
| 2017 | 25 MPG | 22 | 29 | $3100 | 360 | 1 |
Where a model year offered several engines or drivetrains, the figure is the average across all EPA-tested trims that year — the trim count is shown so you can see how much averaging is involved.
SOURCE·US EPA fuel-economy test data·FUEL ASSUMED AT $3.20/GAL FROM JUL 2026·REVIEWED JUL 2026
Marked against the rest of the subcompact cars bay
Among the 229 subcompact cars models tracked here, the Mercedes-Benz C300 4matic Convertible ranks 74 on current figures, against a class average of 24.2 MPG — the square tick on the gauge above.
Closest more-efficient alternatives in the same class: Nissan Sentra/200SX (25.5), Toyota Celica (25.8), Audi A5 Cabriolet (26), Audi A5 quattro (26), Audi S3 (26).
Tailpipe CO₂ is rated at 358 grams per mile, which works out to roughly 5.4 tonnes a year at 15,000 miles.
Questions asked across the counter
What MPG does the Mercedes-Benz C300 4matic Convertible get?
The 2023 Mercedes-Benz C300 4matic Convertible is rated at 25 MPG combined by the EPA — 21 city and 30 highway. Across all 7 model years in the database it averages 24.6 MPG, ranging from 24 to 25 depending on year and trim.
How much does a Mercedes-Benz C300 4matic Convertible cost in fuel per year?
At 25 MPG and 15,000 miles a year, it burns about 600 gallons — roughly $1920 a year with fuel at $3.20 a gallon, or $0.128 per mile. The EPA's own published annual figure for the 2023 model is $3100.
Has the Mercedes-Benz C300 4matic Convertible become more efficient over time?
Barely. It sits at 25 MPG today against 25 in 2017 — essentially flat across 7 model years, with efficiency gains offset by weight and power creep.
Is the Mercedes-Benz C300 4matic Convertible efficient for its class?
It ranks 74 of 229 in the Subcompact Cars class on current figures, against a class average of 24.2 MPG. That is 0.8 better than typical for the class.
Pull another logbook off the same shelf
Same class, nearest economy first — the ones a buyer is genuinely choosing between.
SOURCE·US EPA fuel-economy test data·FUEL ASSUMED AT $3.20/GAL FROM JUL 2026·REVIEWED JUL 2026
Cost per mile, per kilometre and per year are computed at a reference price of $3.20 a gallon over 15,000 miles, fixed JUL 2026 — set your own pump price. Estimates based on official test figures and average fuel prices. Real-world consumption varies with driving style, load, terrain and maintenance.
