Porsche 718 Boxster S
What it costs to keep fuelled
$2,233a year, fuel only
The 2025 Porsche 718 Boxster S is EPA-rated at 21.5 MPG combined (19 city / 24.5 highway). Over 15,000 miles a year that is about 698 gallons, $2233 a year in fuel, or $0.149 per mile at $3.20/gal.
Across its full 2021–2025 run it averages 21.5 MPG, essentially flat across 5 model years.
The band is how far one gallon carries it: 21.5 of the 60 MPG this scale runs to. The square tick is the two seaters average, 21.4.
- Fuel, per year
- $2,233 at 15,000 mi
- Per mile
- $0.149
- Per kilometre
- $0.092
- Gallons burned/yr
- 698
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 | $0.116 | $1163 | $1744 | $2326 |
| $3.00/gal | $0.140 | $1395 | $2093 | $2791 |
| $3.20/gal | $0.149 | $1488 | $2233 | $2977 |
| $3.50/gal | $0.163 | $1628 | $2442 | $3256 |
| $4.00/gal | $0.186 | $1860 | $2791 | $3721 |
| $4.50/gal | $0.209 | $2093 | $3140 | $4186 |
| $5.00/gal | $0.233 | $2326 | $3488 | $4651 |
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
5 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 |
|---|---|---|---|---|---|---|
| 2025 | 21.5 MPG | 19 | 24.5 | $3575 | 417 | 2 |
| 2024 | 21.5 MPG | 19 | 24.5 | $3575 | 417 | 2 |
| 2023 | 21.5 MPG | 19 | 24.5 | $3575 | 417 | 2 |
| 2022 | 21.5 MPG | 19 | 24.5 | $3575 | 417 | 2 |
| 2021 | 21.5 MPG | 19 | 24.5 | $3575 | 417 | 2 |
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 two seaters bay
Among the 105 two seaters models tracked here, the Porsche 718 Boxster S ranks 35 on current figures, against a class average of 21.4 MPG — the square tick on the gauge above.
Closest more-efficient alternatives in the same class: Mazda MX-5 Miata (21.8), Alfa Romeo Spider (22), Bertone X1/9 (22), Jaguar F-Type S Convertible (22), Jaguar F-Type S Coupe (22).
Tailpipe CO₂ is rated at 417 grams per mile, which works out to roughly 6.3 tonnes a year at 15,000 miles.
Questions asked across the counter
What MPG does the Porsche 718 Boxster S get?
The 2025 Porsche 718 Boxster S is rated at 21.5 MPG combined by the EPA — 19 city and 24.5 highway. Across all 5 model years in the database it averages 21.5 MPG, ranging from 21 to 22 depending on year and trim.
How much does a Porsche 718 Boxster S cost in fuel per year?
At 21.5 MPG and 15,000 miles a year, it burns about 698 gallons — roughly $2233 a year with fuel at $3.20 a gallon, or $0.149 per mile. The EPA's own published annual figure for the 2025 model is $3575.
Has the Porsche 718 Boxster S become more efficient over time?
Barely. It sits at 21.5 MPG today against 21.5 in 2021 — essentially flat across 5 model years, with efficiency gains offset by weight and power creep.
Is the Porsche 718 Boxster S efficient for its class?
It ranks 35 of 105 in the Two Seaters class on current figures, against a class average of 21.4 MPG. That is 0.1 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.
