The Mitsubishi Diamante does 18.4 mpg combined (15.9 city, 23 highway), which works out to about $2,087 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 19 mpg while 3.5L 6-cyl does 18.1 — a difference of $101 a year. Against other V6 cars it sits below the average of 19.9 mpg.
Every Mitsubishi Diamante engine, compared
Gas mileage on the Mitsubishi Diamante ranges from 19 down to 18.1 depending on which engine sits under the bonnet — a spread of $101 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 | 16.2 / 23 | 1992–1996 | $2,021 | |
| 3.5L 6-cyl | 15.8 / 23 | 1997–2005 | $2,122 |
What that actually costs
The Mitsubishi Diamante burns a gallon every 18.4 miles, so 12,000 miles takes about 652 gallons a year. At $3.20 that is what the table below adds up to.
| Measure | Value |
|---|---|
| Cost per mile | $0.174 |
| Fuel per year | $2,087 |
| Fuel over five years | $10,435 |
| Against other V6 cars | +$157 a year |
| EPA's own estimate | $4,193 a year |
City or highway — who is this car for
The Mitsubishi Diamante gives up 7.1 mpg the moment you leave the motorway — 23 out there against 15.9 in town, a 45% drop worth $745 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 | 15.9 mpg | $2,415 a year if you only drive in town |
| Highway | 23 mpg | $1,670 a year if you mostly commute |
| Gap | +7.1 mpg (45%) | Wide — this car dislikes traffic |
How the Diamante changed over the years
The Diamante peaked in 1997 at 19 mpg (16 city, 24 highway) and was at its thirstiest in 2005 at 18 — 1 mpg apart, or $112 a year in fuel between buying one year and the other. The 2005 car does 18. 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 |
|---|---|---|---|---|
| 2005 | 15 / 23 | 1 | $2,133 | |
| 2004 | 15 / 23 | 1 | $2,133 | |
| 2003 | 16 / 23 | 1 | $2,133 | |
| 2002 | 16 / 23 | 1 | $2,133 | |
| 2001 | 16 / 23 | 1 | $2,133 | |
| 2000 | 16 / 23 | 1 | $2,133 | |
| 1999 | 16 / 22 | 1 | $2,133 | |
| 1998 | 16 / 23 | 1 | $2,133 | |
| 1997 | 16 / 24 | 1 | $2,021 | |
| 1996 | 16 / 23 | 1 | $2,021 | |
| 1995 | 16 / 23 | 1 | $2,021 | |
| 1994 | 16 / 23 | 1 | $2,021 | |
| 1993 | 17 / 23 | 1 | $2,021 | |
| 1992 | 16 / 23 | 1 | $2,021 |
MPG is a number. Dollars per year is the answer.
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How we count
This page rests on 14 EPA ratings of the Mitsubishi Diamante — 2 engines across 1992–2005. 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 $4,193. Full method.
Frequently asked questions
What mpg does the Mitsubishi Diamante get?
18.4 mpg combined on average — 15.9 in the city and 23 on the highway, per EPA ratings across 1992–2005.
How much does a Mitsubishi Diamante cost in fuel per year?
About $2,087 at 12,000 miles and $3.20 a gallon — roughly $10,435 over five years, or 0.174 dollars a mile.
Which Diamante engine is the most economical?
The 3L 6-cyl at 19 mpg, against 18.1 for the 3.5L 6-cyl — a difference of about $101 a year.
Is the Diamante good on fuel compared with similar cars?
Against other V6 cars it sits below the average of 19.9 mpg, computed across 4940 ratings.
Are these real-world Diamante figures?
No — they are EPA laboratory ratings, the same ones printed on the window sticker, and EPA's own annual fuel estimate for the Mitsubishi Diamante is $4,193 against the $2,087 we compute at 12,000 miles. Expect a little worse in practice: the spread between the 19 and 18 mpg versions of this car is smaller than the spread between two drivers of the same one.
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