1998 BMW 328i Convertible MPG & Specs — Real-World vs EPA, All Trims
Every trim takes regular — no premium needed.
Is the 1998 BMW 328i Convertible good on gas?
At up to 20 MPG combined, the 1998 BMW 328i Convertible is about average for a Minicompact Cars — that class averages about 21.0 MPG across 1,649 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.
This 1998 model was originally EPA-tested under the pre-2008 2-cycle method, which didn't account for highway speeds over 60 mph, air-conditioner use, or cold starts. When EPA overhauled the test for model year 2008, city ratings fell by about 12% and highway by about 8% on average industry-wide — and EPA retroactively adjusted every 1984-2007 rating to the stricter standard so old and new cars could be compared fairly. The MPG above is already on that modern scale — the window sticker on this car when it was new likely showed a higher, pre-2008-method number.
At today's AAA national average price — $3.80/gal for regular gas as of 2026-07-05 — the most efficient trim runs about $2,850/year (roughly $238/month, about $19.00 per 100 miles) at the EPA's assumed 15,000 miles/year, using an estimated 750 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 →
1998 BMW 328i Convertible trims & fuel economy
| Trim (engine / transmission) | Fuel | MPG | Fuel/yr (today's price) |
|---|---|---|---|
| 2.8L 6-cyl, 5-spd manual, RWD | REGULAR | 20 | $2,850 |
| 2.8L 6-cyl, Automatic 4-spd, RWD | REGULAR | 19 | $3,000 |
1998 BMW 328i 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 | 2.8L 6-cyl |
| Transmission | 5-spd manual · Automatic 4-spd |
| Drive type | RWD |
| EPA body class | Minicompact Cars |
| Fuel | Regular |
Other years of the BMW 328i Convertible
Similar cars (Minicompact Cars)
Cars that take premium · Cheapest cars to fuel · Where fuel grade depends on the trim · Fuel guides
2 trim(s) · EPA FuelEconomy.gov data retrieved 2026-07-24 · fuel prices AAA national average as of 2026-07-05.