2018 GMC Sierra K15 4WD (6.2L 8-cyl, Automatic 8-spd) MPG & Specs
Quick answer
The 2018 GMC Sierra K15 4WD gets an EPA-estimated 15/20 MPG (city/highway) and 17 MPG combined, with an estimated $4,450/year fuel cost and 524 g/mi CO₂. Engine: 6.2 L 8-cyl.
The 2018 GMC Sierra K15 4WD with the 6.2-liter 8-cylinder premium gasoline engine returns an EPA-estimated 15 MPG in the city and 20 MPG on the highway, for a combined 17 MPG. This page summarizes the official EPA fuel-economy and emissions data for this configuration.
| Engine | 6.2 L 8-cyl |
| Transmission | Automatic 8-spd |
| Drive | 4-Wheel Drive |
| Fuel type | Premium Gasoline |
| Vehicle class | Standard Pickup Trucks 4WD |
| MPG — city | 15 |
| MPG — highway | 20 |
| MPG — combined | 17 |
| Annual fuel cost* | $4,450 |
| CO₂ tailpipe | 524 g/mi |
| EPA GHG score | 3/10 |
How efficient is it?
With a combined 17 MPG, the 2018 GMC Sierra K15 4WD sits in the low range for fuel economy. That is roughly 20% thirstier than the typical Standard Pickup Trucks 4WD of its era (21 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 2018 GMC Sierra K15 4WD. Over five years that is roughly $22,250 at today's prices — before insurance, maintenance, and depreciation.
Emissions
The 2018 GMC Sierra K15 4WD emits approximately 524 grams of CO₂ per mile at the tailpipe, earning an EPA greenhouse-gas score of 3 out of 10. 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.