The BMW 840i does 24.4 mpg combined (21.6 city, 29.1 highway), which works out to about $1,574 a year in fuel at $3.20 a gallon and 12,000 miles. Against other V6 cars it sits above the average of 19.9 mpg.
Every BMW 840i engine, compared
The BMW 840i was rated in a single specification, so its gas mileage does not vary by version — only by model year. Yearly cost assumes 12,000 miles at $3.20 a gallon.
| Engine | Combined | City / Highway | Years | Fuel per year |
|---|---|---|---|---|
| 3L 6-cyl | 21.6 / 29.1 | 2020–2026 | $1,574 |
What that actually costs
The BMW 840i burns a gallon every 24.4 miles, so 12,000 miles takes about 492 gallons a year. At $3.20 that is what the table below adds up to.
| Measure | Value |
|---|---|
| Cost per mile | $0.131 |
| Fuel per year | $1,574 |
| Fuel over five years | $7,870 |
| Against other V6 cars | −$356 a year |
| EPA's own estimate | $3,157 a year |
City or highway — who is this car for
The BMW 840i gives up 7.5 mpg the moment you leave the motorway — 29.1 out there against 21.6 in town, a 35% drop worth $458 a year. A wide gap punishes stop-and-start traffic; a narrow one means the car doesn't care where you drive it.
| Measure | Value | Reading |
|---|---|---|
| City | 21.6 mpg | $1,778 a year if you only drive in town |
| Highway | 29.1 mpg | $1,320 a year if you mostly commute |
| Gap | +7.5 mpg (35%) | Wide — this car dislikes traffic |
How the 840i changed over the years
The 840i peaked in 2022 at 25 mpg (22 city, 29 highway) and was at its thirstiest in 2026 at 24 — 1 mpg apart, or $64 a year in fuel between buying one year and the other. The 2026 car does 24. Jumps usually mark a new generation or a new engine; dips often mean a heavier body or added all-wheel drive.
| Model year | Combined | City / Highway | Engines offered | Fuel per year |
|---|---|---|---|---|
| 2026 | 21 / 29 | 1 | $1,600 | |
| 2025 | 21 / 29 | 1 | $1,600 | |
| 2024 | 21 / 29 | 1 | $1,600 | |
| 2023 | 21 / 29 | 1 | $1,600 | |
| 2022 | 22 / 29 | 1 | $1,536 | |
| 2021 | 22 / 29 | 1 | $1,536 | |
| 2020 | 23 / 30 | 1 | $1,536 |
MPG is a number. Dollars per year is the answer.
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How we count
This page rests on 7 EPA ratings of the BMW 840i — 1 engine across 2020–2026. The mileage is EPA's laboratory figure, unchanged; the yearly bill is ours, at 12,000 miles and $3.20 a gallon, against EPA's own estimate of $3,157. Full method.
Frequently asked questions
What mpg does the BMW 840i get?
24.4 mpg combined on average — 21.6 in the city and 29.1 on the highway, per EPA ratings across 2020–2026.
How much does a BMW 840i cost in fuel per year?
About $1,574 at 12,000 miles and $3.20 a gallon — roughly $7,870 over five years, or 0.131 dollars a mile.
Which 840i engine is the most economical?
The 3L 6-cyl at 24.4 mpg.
Is the 840i good on fuel compared with similar cars?
Against other V6 cars it sits above the average of 19.9 mpg, computed across 4940 ratings.
Are these real-world 840i figures?
No — they are EPA laboratory ratings, the same ones printed on the window sticker, and EPA's own annual fuel estimate for the BMW 840i is $3,157 against the $1,574 we compute at 12,000 miles. Expect a little worse in practice: the spread between the city and highway figures is smaller than the spread between two drivers of the same one.
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