The Porsche Cayman does 23.9 mpg combined (20.8 city, 29 highway), which works out to about $1,607 a year in fuel at $3.20 a gallon and 12,000 miles. Engine choice matters more than you'd think: 2L 4-cyl does 24.8 mpg while 3.4L 6-cyl does 21 — a difference of $281 a year. Against other V6 cars it sits above the average of 19.9 mpg.
Every Porsche Cayman engine, compared
Gas mileage on the Porsche Cayman ranges from 24.8 down to 21 depending on which engine sits under the bonnet — a spread of $281 a year across 4 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 |
|---|---|---|---|---|
| 2L 4-cyl | 21.8 / 28.5 | 2017–2020 | $1,548 | |
| 2.7L 6-cyl | 21.2 / 30.2 | 2007–2016 | $1,587 | |
| 2.9L 6-cyl | 20 / 29 | 2009–2012 | $1,634 | |
| 3.4L 6-cyl | 18 / 25 | 2006–2006 | $1,829 |
What that actually costs
The Porsche Cayman burns a gallon every 23.9 miles, so 12,000 miles takes about 502 gallons a year. At $3.20 that is what the table below adds up to.
| Measure | Value |
|---|---|
| Cost per mile | $0.134 |
| Fuel per year | $1,607 |
| Fuel over five years | $8,035 |
| Against other V6 cars | −$323 a year |
| EPA's own estimate | $3,232 a year |
City or highway — who is this car for
The Porsche Cayman gives up 8.2 mpg the moment you leave the motorway — 29 out there against 20.8 in town, a 39% drop worth $522 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 | 20.8 mpg | $1,846 a year if you only drive in town |
| Highway | 29 mpg | $1,324 a year if you mostly commute |
| Gap | +8.2 mpg (39%) | Wide — this car dislikes traffic |
How the Cayman changed over the years
The Cayman peaked in 2019 at 25 mpg (22 city, 29 highway) and was at its thirstiest in 2006 at 21 — 4 mpg apart, or $293 a year in fuel between buying one year and the other. The 2020 car does 24. 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 |
|---|---|---|---|---|
| 2020 | 21 / 27 | 1 | $1,600 | |
| 2019 | 22 / 29 | 1 | $1,536 | |
| 2018 | 22 / 29 | 1 | $1,536 | |
| 2017 | 22 / 29 | 1 | $1,536 | |
| 2016 | 22 / 31 | 1 | $1,536 | |
| 2015 | 22 / 31 | 1 | $1,536 | |
| 2014 | 22 / 31 | 1 | $1,536 | |
| 2012 | 20 / 29 | 1 | $1,670 | |
| 2011 | 20 / 29 | 1 | $1,670 | |
| 2010 | 20 / 29 | 1 | $1,600 | |
| 2009 | 20 / 29 | 1 | $1,600 | |
| 2008 | 20 / 29 | 1 | $1,670 | |
| 2007 | 20 / 29 | 1 | $1,670 | |
| 2006 | 18 / 25 | 1 | $1,829 |
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 Porsche Cayman — 4 engines across 2006–2020. 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 $3,232. Full method.
Frequently asked questions
What mpg does the Porsche Cayman get?
23.9 mpg combined on average — 20.8 in the city and 29 on the highway, per EPA ratings across 2006–2020.
How much does a Porsche Cayman cost in fuel per year?
About $1,607 at 12,000 miles and $3.20 a gallon — roughly $8,035 over five years, or 0.134 dollars a mile.
Which Cayman engine is the most economical?
The 2L 4-cyl at 24.8 mpg, against 21 for the 3.4L 6-cyl — a difference of about $281 a year.
Is the Cayman 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 Cayman figures?
No — they are EPA laboratory ratings, the same ones printed on the window sticker, and EPA's own annual fuel estimate for the Porsche Cayman is $3,232 against the $1,607 we compute at 12,000 miles. Expect a little worse in practice: the spread between the 25 and 21 mpg versions of this car is smaller than the spread between two drivers of the same one.
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