2014 BMW 640i Convertible MPG & Specs — Real-World vs EPA, All Trims
Every gas trim of this model takes premium.
Is the 2014 BMW 640i Convertible good on gas?
At up to 23 MPG combined, the 2014 BMW 640i Convertible is about average for a Subcompact Cars — that class averages about 22.8 MPG across 5,756 EPA-tested versions, so it's middle-of-the-road for its size.
Real-world MPG vs the EPA number
The EPA figures above come from a standardized dynamometer test, not the open road — real-world MPG typically runs a bit lower depending on your driving, climate and terrain. That's true of every car on this site, old or new.
EPA updated its fuel-economy equations again for model year 2017 — mostly affecting hybrids and turbocharged engines — and recalculated 2011-2016 ratings to match, in some cases 1-2 MPG lower. The number above already reflects that update.
At today's AAA national average price — $4.68/gal for premium gas as of 2026-07-05 — the most efficient trim runs about $3,052/year (roughly $254/month, about $20.35 per 100 miles) at the EPA's assumed 15,000 miles/year, using an estimated 652 gallons a year. We don't estimate a cost-per-fill since exact tank size isn't in the public EPA dataset, but the per-100-mile figure scales to any tank. Current national average gas prices →
2014 BMW 640i Convertible trims & fuel economy
| Trim (engine / transmission) | Fuel | MPG | Fuel/yr (today's price) |
|---|---|---|---|
| 3.0L 6-cyl, S8 automatic, RWD | PREMIUM | 23 | $3,052 |
2014 BMW 640i Convertible specs
What the EPA test-car listings record for this model year — every combination sold is a row in the trims table above.
| Engine options | 3.0L 6-cyl turbo |
| Transmission | S8 automatic |
| Drive type | RWD |
| EPA body class | Subcompact Cars |
| Fuel | Premium |
| Tailpipe CO₂ | 378 g/mi |
Other years of the BMW 640i Convertible
Similar cars (Subcompact Cars)
Cars that take premium · Cheapest cars to fuel · Where fuel grade depends on the trim · Fuel guides
1 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.