The Infiniti Q45 does 17.6 mpg combined (15.6 city, 21.1 highway), which works out to about $2,182 a year in fuel at $3.20 a gallon and 12,000 miles. Engine choice matters more than you'd think: 4.1L 8-cyl does 18 mpg while 4.5L 8-cyl does 17.4 — a difference of $74 a year. Against other V8 cars it sits above the average of 16.1 mpg.
Every Infiniti Q45 engine, compared
Gas mileage on the Infiniti Q45 ranges from 18 down to 17.4 depending on which engine sits under the bonnet — a spread of $74 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 |
|---|---|---|---|---|
| 4.1L 8-cyl | 16 / 21.6 | 1997–2001 | $2,133 | |
| 4.5L 8-cyl | 15.4 / 20.9 | 1990–2006 | $2,207 |
What that actually costs
The Infiniti Q45 burns a gallon every 17.6 miles, so 12,000 miles takes about 682 gallons a year. At $3.20 that is what the table below adds up to.
| Measure | Value |
|---|---|
| Cost per mile | $0.182 |
| Fuel per year | $2,182 |
| Fuel over five years | $10,910 |
| Against other V8 cars | −$203 a year |
| EPA's own estimate | $4,403 a year |
City or highway — who is this car for
The Infiniti Q45 gives up 5.5 mpg the moment you leave the motorway — 21.1 out there against 15.6 in town, a 35% drop worth $642 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 | 15.6 mpg | $2,462 a year if you only drive in town |
| Highway | 21.1 mpg | $1,820 a year if you mostly commute |
| Gap | +5.5 mpg (35%) | Wide — this car dislikes traffic |
How the Q45 changed over the years
The Q45 peaked in 2006 at 18 mpg (16 city, 22 highway) and was at its thirstiest in 1996 at 17 — 1 mpg apart, or $126 a year in fuel between buying one year and the other. The 2006 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 |
|---|---|---|---|---|
| 2006 | 16 / 22 | 1 | $2,133 | |
| 2005 | 16 / 22 | 1 | $2,133 | |
| 2004 | 16 / 22 | 1 | $2,133 | |
| 2003 | 16 / 22 | 1 | $2,133 | |
| 2002 | 16 / 23 | 1 | $2,133 | |
| 2001 | 16 / 21 | 1 | $2,133 | |
| 2000 | 16 / 21 | 1 | $2,133 | |
| 1999 | 16 / 22 | 1 | $2,133 | |
| 1998 | 16 / 22 | 1 | $2,133 | |
| 1997 | 16 / 22 | 1 | $2,133 | |
| 1996 | 15 / 20 | 1 | $2,259 | |
| 1995 | 15 / 20 | 1 | $2,259 | |
| 1994 | 15 / 20 | 1 | $2,259 | |
| 1993 | 15 / 20 | 1 | $2,259 | |
| 1992 | 15 / 20 | 1 | $2,259 | |
| 1991 | 15 / 20 | 1 | $2,259 | |
| 1990 | 15 / 20 | 1 | $2,259 |
MPG is a number. Dollars per year is the answer.
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How we count
This page rests on 17 EPA ratings of the Infiniti Q45 — 2 engines across 1990–2006. 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 $4,403. Full method.
Frequently asked questions
What mpg does the Infiniti Q45 get?
17.6 mpg combined on average — 15.6 in the city and 21.1 on the highway, per EPA ratings across 1990–2006.
How much does a Infiniti Q45 cost in fuel per year?
About $2,182 at 12,000 miles and $3.20 a gallon — roughly $10,910 over five years, or 0.182 dollars a mile.
Which Q45 engine is the most economical?
The 4.1L 8-cyl at 18 mpg, against 17.4 for the 4.5L 8-cyl — a difference of about $74 a year.
Is the Q45 good on fuel compared with similar cars?
Against other V8 cars it sits above the average of 16.1 mpg, computed across 3323 ratings.
Are these real-world Q45 figures?
No — they are EPA laboratory ratings, the same ones printed on the window sticker, and EPA's own annual fuel estimate for the Infiniti Q45 is $4,403 against the $2,182 we compute at 12,000 miles. Expect a little worse in practice: the spread between the 18 and 17 mpg versions of this car is smaller than the spread between two drivers of the same one.
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