The BMW 328iS does 20.9 mpg combined (17.9 city, 26.5 highway), which works out to about $1,837 a year in fuel at $3.20 a gallon and 12,000 miles. Engine choice matters more than you'd think: 3L 6-cyl does 21 mpg while 2.8L 6-cyl does 20.8 — a difference of $17 a year. Against other V6 cars it sits above the average of 19.9 mpg.
Every BMW 328iS engine, compared
Gas mileage on the BMW 328iS ranges from 21 down to 20.8 depending on which engine sits under the bonnet — a spread of $17 a year across 2 versions of the same car. Picking the right one often saves more fuel than picking a different car altogether. Yearly cost assumes 12,000 miles at $3.20 a gallon.
| Engine | Combined | City / Highway | Years | Fuel per year |
|---|---|---|---|---|
| 3L 6-cyl | 18 / 26.7 | 2007–2012 | $1,829 | |
| 2.8L 6-cyl | 17.8 / 26.3 | 1996–1999 | $1,846 |
What that actually costs
The BMW 328iS burns a gallon every 20.9 miles, so 12,000 miles takes about 574 gallons a year. At $3.20 that is what the table below adds up to.
| Measure | Value |
|---|---|
| Cost per mile | $0.153 |
| Fuel per year | $1,837 |
| Fuel over five years | $9,185 |
| Against other V6 cars | −$93 a year |
| EPA's own estimate | $3,525 a year |
City or highway — who is this car for
The BMW 328iS gives up 8.6 mpg the moment you leave the motorway — 26.5 out there against 17.9 in town, a 48% drop worth $696 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 | 17.9 mpg | $2,145 a year if you only drive in town |
| Highway | 26.5 mpg | $1,449 a year if you mostly commute |
| Gap | +8.6 mpg (48%) | Wide — this car dislikes traffic |
How the 328iS changed over the years
The 328iS peaked in 2012 at 21 mpg (18 city, 26 highway) and was at its thirstiest in 1998 at 20 — 1 mpg apart, or $91 a year in fuel between buying one year and the other. The 2012 car does 21. 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 |
|---|---|---|---|---|
| 2012 | 18 / 26 | 1 | $1,829 | |
| 2011 | 18 / 26 | 1 | $1,829 | |
| 2010 | 18 / 27 | 1 | $1,829 | |
| 2009 | 18 / 27 | 1 | $1,829 | |
| 2008 | 18 / 27 | 1 | $1,829 | |
| 2007 | 18 / 27 | 1 | $1,829 | |
| 1999 | 18 / 27 | 1 | $1,829 | |
| 1998 | 17 / 26 | 1 | $1,920 | |
| 1997 | 18 / 26 | 1 | $1,829 | |
| 1996 | 18 / 26 | 1 | $1,829 |
MPG is a number. Dollars per year is the answer.
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How we count
This page rests on 10 EPA ratings of the BMW 328iS — 2 engines across 1996–2012. 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 $3,525. Full method.
Frequently asked questions
What mpg does the BMW 328iS get?
20.9 mpg combined on average — 17.9 in the city and 26.5 on the highway, per EPA ratings across 1996–2012.
How much does a BMW 328iS cost in fuel per year?
About $1,837 at 12,000 miles and $3.20 a gallon — roughly $9,185 over five years, or 0.153 dollars a mile.
Which 328iS engine is the most economical?
The 3L 6-cyl at 21 mpg, against 20.8 for the 2.8L 6-cyl — a difference of about $17 a year.
Is the 328iS 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 328iS 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 328iS is $3,525 against the $1,837 we compute at 12,000 miles. Expect a little worse in practice: the spread between the 21 and 20 mpg versions of this car is smaller than the spread between two drivers of the same one.
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