BMW Z4 M40i
23.5 MPG The 2026 BMW Z4 M40i is EPA-rated at 23.5 MPG combined (21 city / 27.5 highway). Over 15,000 miles a year that is about 638 gallons, $2043 a year in fuel, or $0.136 per mile at $3.20/gal.
Across its full 2020–2026 run it averages 25 MPG, falling by 2.5 MPG over 7 model years.
Running cost at different fuel prices and mileages
The figure everyone actually wants, and the one the EPA does not publish — because it depends on a fuel price no agency will commit to.
| Fuel price | Per mile | 10,000 mi/yr | 15,000 mi/yr | 20,000 mi/yr |
|---|---|---|---|---|
| $2.50/gal | $0.106 | $1064 | $1596 | $2128 |
| $3.00/gal | $0.128 | $1277 | $1915 | $2553 |
| $3.20/gal | $0.136 | $1362 | $2043 | $2723 |
| $3.50/gal | $0.149 | $1489 | $2234 | $2979 |
| $4.00/gal | $0.170 | $1702 | $2553 | $3404 |
| $4.50/gal | $0.191 | $1915 | $2872 | $3830 |
| $5.00/gal | $0.213 | $2128 | $3191 | $4255 |
Every model year
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 2026 | 23.5 MPG | 21 | 27.5 | $3300 | 377 | 2 |
| 2025 | 23.5 MPG | 21 | 27.5 | $3300 | 377 | 2 |
| 2024 | 26 MPG | 23 | 31 | $2950 | 338 | 1 |
| 2023 | 26 MPG | 23 | 31 | $2950 | 338 | 1 |
| 2022 | 25 MPG | 22 | 29 | $3100 | 358 | 1 |
| 2021 | 25 MPG | 22 | 30 | $3100 | 355 | 1 |
| 2020 | 26 MPG | 24 | 31 | $2950 | 334 | 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.
How it compares in its class
Among the 105 two seaters models tracked here, the BMW Z4 M40i ranks 21 on current figures, against a class average of 21.4 MPG.
Closest more-efficient alternatives in the same class: Mercedes-Benz SLK350 (24), Toyota GR Supra (24.3), Audi TT Roadster (25), Toyota MR2 (25.5), Audi TT Roadster quattro (26).
Tailpipe CO₂ is rated at 377 grams per mile, which works out to roughly 5.7 tonnes a year at 15,000 miles.
Questions
What MPG does the BMW Z4 M40i get?
The 2026 BMW Z4 M40i is rated at 23.5 MPG combined by the EPA — 21 city and 27.5 highway. Across all 7 model years in the database it averages 25 MPG, ranging from 22 to 26 depending on year and trim.
How much does a BMW Z4 M40i cost in fuel per year?
At 23.5 MPG and 15,000 miles a year, it burns about 638 gallons — roughly $2043 a year with fuel at $3.20 a gallon, or $0.136 per mile. The EPA's own published annual figure for the 2026 model is $3300.
Has the BMW Z4 M40i become more efficient over time?
No — it has actually gone backwards, from 26 MPG in 2020 to 23.5 in 2026. That usually reflects the model growing heavier, more powerful, or moving upmarket rather than the engineering getting worse.
Is the BMW Z4 M40i efficient for its class?
It ranks 21 of 105 in the Two Seaters class on current figures, against a class average of 21.4 MPG. That is 2.1 better than typical for the class.
EPA test figures from fueleconomy.gov. Cost per mile and annual fuel spend are computed at a reference price of $3.20 per gallon — use your own price. Estimates based on official test figures and average fuel prices. Real-world consumption varies with driving style, load, terrain and maintenance.