BMW 840i xDrive Convertible
24 MPG The 2026 BMW 840i xDrive Convertible is EPA-rated at 24 MPG combined (21 city / 29 highway). Over 15,000 miles a year that is about 625 gallons, $2000 a year in fuel, or $0.133 per mile at $3.20/gal.
Across its full 2020–2026 run it averages 23.6 MPG, improving by 1 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 | $0.104 | $1042 | $1563 | $2083 |
| $3.00/gal | $0.125 | $1250 | $1875 | $2500 |
| $3.20/gal | $0.133 | $1333 | $2000 | $2667 |
| $3.50/gal | $0.146 | $1458 | $2188 | $2917 |
| $4.00/gal | $0.167 | $1667 | $2500 | $3333 |
| $4.50/gal | $0.188 | $1875 | $2813 | $3750 |
| $5.00/gal | $0.208 | $2083 | $3125 | $4167 |
Every model year
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 2026 | 24 MPG | 21 | 29 | $3200 | 373 | 1 |
| 2025 | 24 MPG | 21 | 29 | $3200 | 373 | 1 |
| 2024 | 24 MPG | 21 | 29 | $3200 | 373 | 1 |
| 2023 | 24 MPG | 21 | 29 | $3200 | 373 | 1 |
| 2022 | 23 MPG | 20 | 27 | $3350 | 388 | 1 |
| 2021 | 23 MPG | 20 | 27 | $3350 | 387 | 1 |
| 2020 | 23 MPG | 20 | 27 | $3350 | 388 | 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 229 subcompact cars models tracked here, the BMW 840i xDrive Convertible ranks 88 on current figures, against a class average of 24.2 MPG.
Closest more-efficient alternatives in the same class: Mazda MX-3 (24.3), Ford Laser (24.5), Acura RSX (24.7), Audi A3 Cabriolet quattro (25), Audi A4 Cabriolet (25).
Tailpipe CO₂ is rated at 373 grams per mile, which works out to roughly 5.6 tonnes a year at 15,000 miles.
Questions
What MPG does the BMW 840i xDrive Convertible get?
The 2026 BMW 840i xDrive Convertible is rated at 24 MPG combined by the EPA — 21 city and 29 highway. Across all 7 model years in the database it averages 23.6 MPG, ranging from 23 to 24 depending on year and trim.
How much does a BMW 840i xDrive Convertible cost in fuel per year?
At 24 MPG and 15,000 miles a year, it burns about 625 gallons — roughly $2000 a year with fuel at $3.20 a gallon, or $0.133 per mile. The EPA's own published annual figure for the 2026 model is $3200.
Has the BMW 840i xDrive Convertible become more efficient over time?
Yes. It has gone from 23 MPG in 2020 to 24 in 2026 — an improvement of 1 MPG, or 4% across 7 model years.
Is the BMW 840i xDrive Convertible efficient for its class?
It ranks 88 of 229 in the Subcompact Cars class on current figures, against a class average of 24.2 MPG. That is 0.2 worse 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.