- Newest year: 2006
- Gas
- Midsize cars
2005-2006 Cadillac STS MPG & Fuel Cost
2 model years · 17–19 MPG combined
15,000 mi/yr · regular gasoline $4.36/gal (U.S. average, Sep 2026)
Cheaper to fuel than 5 of 10 midsize car configurations, MY2006. Ranked against all rated configurations, not sales-weighted.
2005-2006 Cadillac STS at a glance
The 2005-2006 Cadillac STS covers 2 model years in the EPA database (7 configurations in all), rated 17–19 MPG combined. The newest model year, 2006, costs about $3,440 a year to fuel for its most efficient version, the STS 3.6L 6-cyl RWD (19 MPG), at regular gasoline $4.36/gal (U.S. average, Sep 2026). EPA changed the ratings in 2006. The best combined rating in the generation, 19 MPG, was reached in 2006.
EPA re-estimated ratings of 1985-2007 vehicles under its 2008 method; these figures are the re-estimated values.
2005-2006 Cadillac STS by model year
What the 2006 STS 3.6L 6-cyl RWD costs to drive
Per month
$287
$3,440 a year ÷ 12
Per 25 miles
$5.73
Per 100 miles
$22.93
Five years
$17,200
5 × the yearly cost, prices held at today's level
vs the midsize car median
$190less a year
Class median $3,630 a year, MY2006
Based on 15,000 miles a year and regular gasoline $4.36/gal (U.S. average, Sep 2026).
2006 Cadillac STS MPG
EPA re-estimated ratings of 1985-2007 vehicles under its 2008 method; these figures are the re-estimated values.
Versus 2005: The most efficient configuration moves from 18 to 19 MPG, up 1. Its annual cost goes from $3,630 to $3,440, $190 less.
Gas configurations (4)
| Trim | Engine | Drive | City | Hwy | Comb. | $/yr |
|---|---|---|---|---|---|---|
| STS 3.6L 6-cyl RWD (Most efficient) | 3.6L 6-cyl | RWD | 16 | 25 | 19 | $3,440 |
| STS 3.6L 6-cyl 4WD | 3.6L 6-cyl | 4WD | 15 | 23 | 18 | $3,630 |
| STS 4.6L 8-cyl RWD | 4.6L 8-cyl | RWD | 15 | 24 | 18 | $4,460 |
| STS 4.6L 8-cyl 4WD | 4.6L 8-cyl | 4WD | 14 | 21 | 17 | $4,730 |
2 configurations require or recommend higher-octane gasoline and are costed at premium gasoline $5.36/gal (U.S. average, Sep 2026).
2005 Cadillac STS MPG
17–18 MPG · $3,630–$4,730/yr
EPA re-estimated ratings of 1985-2007 vehicles under its 2008 method; these figures are the re-estimated values.
Gas configurations (3)
| Trim | Engine | Drive | City | Hwy | Comb. | $/yr |
|---|---|---|---|---|---|---|
| STS 3.6L 6-cyl (Most efficient) | 3.6L 6-cyl | RWD | 16 | 23 | 18 | $3,630 |
| STS 4.6L 8-cyl RWD | 4.6L 8-cyl | RWD | 15 | 23 | 18 | $4,460 |
| STS 4.6L 8-cyl 4WD | 4.6L 8-cyl | 4WD | 14 | 21 | 17 | $4,730 |
2 configurations require or recommend higher-octane gasoline and are costed at premium gasoline $5.36/gal (U.S. average, Sep 2026).
Fuel cost by state
Yearly cost of the STS 3.6L 6-cyl RWD: $4,680 in California and $3,000 in Texas, a $1,680 difference.
- California $4,680
- Washington $4,330
- New York $3,440
- Florida $3,250
- Texas $3,000
Similar cars
Closest combined MPG among MY2006 midsize car models.
Generations
Frequently asked questions
What gas mileage does the 2005-2006 Cadillac STS get?
EPA rates the 2005-2006 Cadillac STS at 17–19 MPG combined across 7 configurations and 2 model years. The most efficient version, the 2006 STS 3.6L 6-cyl RWD, is rated 19 MPG (16 city, 25 highway).
Which years had the best MPG in the 2005-2006 Cadillac STS?
The STS 3.6L 6-cyl RWD reached the generation's best combined rating, 19 MPG, in 2006. The lowest top rating, 18 MPG, was in 2005.
Did EPA ratings change during the 2005-2006 Cadillac STS?
Yes. Ratings changed in 2006.
How much does it cost to fuel a 2006 Cadillac STS per year?
Driving 15,000 miles a year at regular gasoline $4.36/gal (U.S. average, Sep 2026), the STS 3.6L 6-cyl RWD costs about $3,440 a year. Across all 4 configurations the cost runs $3,440–$4,730 a year. That is a $1,290 difference between the cheapest and the costliest configuration.
How much does it cost to drive a 2006 Cadillac STS 100 miles?
About $22.93 per 100 miles for the STS 3.6L 6-cyl RWD at regular gasoline $4.36/gal (U.S. average, Sep 2026), and between $22.93 and $31.53 across all configurations. That is the annual cost over 15,000 miles divided by 150.
Is the 2006 Cadillac STS more efficient in the city or on the highway?
The STS 3.6L 6-cyl RWD is rated 16 city and 25 highway MPG, so it is more efficient on the highway, by 9 MPG.
How does the 2006 Cadillac STS compare with other midsize car configurations?
The STS 3.6L 6-cyl RWD costs about $3,440 a year to fuel, $190 less than the class median of $3,630, and less than 5 of 10 midsize car configurations. The comparison covers all 133 rated midsize car configurations for MY2006, not weighted by sales.
Is the 2006 Cadillac STS different from the 2005 model?
The most efficient configuration moves from 18 to 19 MPG, up 1. Its annual cost goes from $3,630 to $3,440, $190 less. EPA lists 4 configurations for 2006 against 3 configurations for 2005. See the 2005 Cadillac STS for that year.