Cadillac STS
21 MPG The 2011 Cadillac STS is EPA-rated at 21 MPG combined (18 city / 27 highway). Over 15,000 miles a year that is about 714 gallons, $2286 a year in fuel, or $0.152 per mile at $3.20/gal.
Across its full 2006–2011 run it averages 19.1 MPG, improving by 2.5 MPG over 6 model years.
Running cost at different fuel prices and mileages
The figure everyone actually wants, and the one the EPA does not publish — because it depends on a fuel price no agency will commit to.
| Fuel price | Per mile | 10,000 mi/yr | 15,000 mi/yr | 20,000 mi/yr |
|---|---|---|---|---|
| $2.50/gal | $0.119 | $1190 | $1786 | $2381 |
| $3.00/gal | $0.143 | $1429 | $2143 | $2857 |
| $3.20/gal | $0.152 | $1524 | $2286 | $3048 |
| $3.50/gal | $0.167 | $1667 | $2500 | $3333 |
| $4.00/gal | $0.190 | $1905 | $2857 | $3810 |
| $4.50/gal | $0.214 | $2143 | $3214 | $4286 |
| $5.00/gal | $0.238 | $2381 | $3571 | $4762 |
Every model year
| Year | Combined | City | Highway | EPA fuel cost/yr | CO₂ g/mi | Trims |
|---|---|---|---|---|---|---|
| 2011 | 21 MPG | 18 | 27 | $2950 | 423 | 1 |
| 2010 | 19.5 MPG | 16.5 | 25.5 | $3200 | 458 | 2 |
| 2009 | 19 MPG | 16 | 25 | $3700 | 469 | 2 |
| 2008 | 19 MPG | 16 | 25 | $3700 | 469 | 2 |
| 2007 | 17.7 MPG | 15 | 23.3 | $4133 | 506 | 3 |
| 2006 | 18.5 MPG | 15.5 | 24.5 | $3800 | 481 | 2 |
Where a model year offered several engines or drivetrains, the figure is the average across all EPA-tested trims that year — the trim count is shown so you can see how much averaging is involved.
How it compares in its class
Among the 261 midsize cars models tracked here, the Cadillac STS ranks 167 on current figures, against a class average of 27.2 MPG.
Closest more-efficient alternatives in the same class: Buick Lacrosse/Allure (21.3), Chevrolet Celebrity (21.3), Chrysler Sebring 4 Door (21.3), Dodge 600 (21.3), Dodge Stratus 4 Door (21.3).
Tailpipe CO₂ is rated at 423 grams per mile, which works out to roughly 6.3 tonnes a year at 15,000 miles.
Questions
What MPG does the Cadillac STS get?
The 2011 Cadillac STS is rated at 21 MPG combined by the EPA — 18 city and 27 highway. Across all 6 model years in the database it averages 19.1 MPG, ranging from 16 to 21 depending on year and trim.
How much does a Cadillac STS cost in fuel per year?
At 21 MPG and 15,000 miles a year, it burns about 714 gallons — roughly $2286 a year with fuel at $3.20 a gallon, or $0.152 per mile. The EPA's own published annual figure for the 2011 model is $2950.
Has the Cadillac STS become more efficient over time?
Yes. It has gone from 18.5 MPG in 2006 to 21 in 2011 — an improvement of 2.5 MPG, or 14% across 6 model years.
Is the Cadillac STS efficient for its class?
It ranks 167 of 261 in the Midsize Cars class on current figures, against a class average of 27.2 MPG. That is 6.2 worse than typical for the class.
EPA test figures from fueleconomy.gov. Cost per mile and annual fuel spend are computed at a reference price of $3.20 per gallon — use your own price. Estimates based on official test figures and average fuel prices. Real-world consumption varies with driving style, load, terrain and maintenance.