2009 Cadillac STS AWD (4.6L 8-cyl) MPG & Specs
Quick answer
The 2009 Cadillac STS AWD gets an EPA-estimated 15/22 MPG (city/highway) and 17 MPG combined, with an estimated $4,450/year fuel cost and 522.765 g/mi CO₂. Engine: 4.6 L 8-cyl.
The 2009 Cadillac STS AWD with the 4.6-liter 8-cylinder premium gasoline engine returns an EPA-estimated 15 MPG in the city and 22 MPG on the highway, for a combined 17 MPG. This page summarizes the official EPA fuel-economy and emissions data for this configuration.
| Engine | 4.6 L 8-cyl |
| Transmission | Automatic (S6) |
| Drive | 4-Wheel or All-Wheel Drive |
| Fuel type | Premium Gasoline |
| Vehicle class | Midsize Cars |
| MPG — city | 15 |
| MPG — highway | 22 |
| MPG — combined | 17 |
| Annual fuel cost* | $4,450 |
| CO₂ tailpipe | 522.765 g/mi |
| EPA GHG score | — |
How efficient is it?
With a combined 17 MPG, the 2009 Cadillac STS AWD sits in the low range for fuel economy. That is roughly 33% thirstier than the typical Midsize Cars of its era (26 MPG class average) — expect higher fuel bills than class-average alternatives.
Fuel economy and running costs
At about $4,450 per year in fuel (EPA estimate, 15,000 mi/yr), fuel is a major part of the cost of owning the 2009 Cadillac STS AWD. Over five years that is roughly $22,250 at today's prices — before insurance, maintenance, and depreciation.
Emissions
The 2009 Cadillac STS AWD emits approximately 522.765 grams of CO₂ per mile at the tailpipe. Lower emissions generally track higher fuel economy.
How to read these numbers
EPA figures come from standardized laboratory test cycles and are the same estimates shown on the vehicle's window sticker. Your real-world mileage depends on driving style, conditions, fuel grade, and maintenance. Use combined MPG and annual fuel cost to compare vehicles fairly.