BMW 640i xDrive Convertible
22 MPG The 2018 BMW 640i xDrive Convertible is EPA-rated at 22 MPG combined (19 city / 28 highway). Over 15,000 miles a year that is about 682 gallons, $2182 a year in fuel, or $0.145 per mile at $3.20/gal.
Across its full 2014–2018 run it averages 22.6 MPG, falling by 1 MPG over 5 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 | $0.114 | $1136 | $1705 | $2273 |
| $3.00/gal | $0.136 | $1364 | $2045 | $2727 |
| $3.20/gal | $0.145 | $1455 | $2182 | $2909 |
| $3.50/gal | $0.159 | $1591 | $2386 | $3182 |
| $4.00/gal | $0.182 | $1818 | $2727 | $3636 |
| $4.50/gal | $0.205 | $2045 | $3068 | $4091 |
| $5.00/gal | $0.227 | $2273 | $3409 | $4545 |
Every model year
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 2018 | 22 MPG | 19 | 28 | $3500 | 396 | 1 |
| 2017 | 22 MPG | 19 | 28 | $3500 | 398 | 1 |
| 2016 | 23 MPG | 20 | 29 | $3350 | 384 | 1 |
| 2015 | 23 MPG | 20 | 29 | $3350 | 385 | 1 |
| 2014 | 23 MPG | 20 | 29 | $3350 | 384 | 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 640i xDrive Convertible ranks 119 on current figures, against a class average of 24.2 MPG.
Closest more-efficient alternatives in the same class: Ford Probe (22.3), BMW M240i Convertible (22.5), Mazda MX-6 (22.5), Saab 9-3 Convertible (22.5), Mitsubishi Cordia (22.7).
Tailpipe CO₂ is rated at 396 grams per mile, which works out to roughly 5.9 tonnes a year at 15,000 miles.
Questions
What MPG does the BMW 640i xDrive Convertible get?
The 2018 BMW 640i xDrive Convertible is rated at 22 MPG combined by the EPA — 19 city and 28 highway. Across all 5 model years in the database it averages 22.6 MPG, ranging from 22 to 23 depending on year and trim.
How much does a BMW 640i xDrive Convertible cost in fuel per year?
At 22 MPG and 15,000 miles a year, it burns about 682 gallons — roughly $2182 a year with fuel at $3.20 a gallon, or $0.145 per mile. The EPA's own published annual figure for the 2018 model is $3500.
Has the BMW 640i xDrive Convertible become more efficient over time?
No — it has actually gone backwards, from 23 MPG in 2014 to 22 in 2018. That usually reflects the model growing heavier, more powerful, or moving upmarket rather than the engineering getting worse.
Is the BMW 640i xDrive Convertible efficient for its class?
It ranks 119 of 229 in the Subcompact Cars class on current figures, against a class average of 24.2 MPG. That is 2.2 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.