2026 GMC Sierra 4WD AT4X with Sport Mode specs & fuel economy
The 2026 GMC Sierra 4WD AT4X with Sport Mode is rated 19 MPG combined by the EPA (19 city, 20 highway). That is 4% above the 18.3 MPG average across the 73 EPA configurations in the 2026 Standard Pickup Trucks 4WD class, placing it in the 65th percentile of its class. At 12,000 miles at $3.50/US gallon it costs about $2,211 a year to run.
EPA data snapshot imported 2026-09-06 · United States · US gallons
The 2026 GMC Sierra 4WD AT4X with Sport Mode has 1 EPA-listed configuration in our 2026-09-06 data snapshot. Listed transmissions: Automatic 10-spd. Compare the engine, drive type and fuel ratings below before matching an individual car by VIN.
How the 2026 GMC Sierra 4WD AT4X with Sport Mode compares in its class
EPA publishes each configuration on its own. Ranking one against every configuration EPA rated in the same class and model year is our calculation from the 2026-09-06 snapshot, not an EPA figure.
- Combined rating
- 19 MPG
- 2026 Standard Pickup Trucks 4WD average
- 18.3 MPG
- Difference
- 4% above average
- Rank in class
- 65th percentile of 73 configurations
- Reference annual energy cost
- $2,211 · 12,000 miles at $3.50/US gallon
The class average covers every 2026 configuration EPA rated in the Standard Pickup Trucks 4WD class, compared in MPG only, so electric and liquid-fuel ratings are never mixed. The reference cost is a fixed assumption for comparison; the calculator below takes your own mileage and prices.
Engine, transmission and fuel economy
The single 2026 Sierra 4WD AT4X with Sport Mode configuration EPA rated, with a link to its source record. Combined primary-fuel ratings: 19 MPG. Missing values remain “Not reported.”
| Engine / transmission / drive | Primary fuel | City | Highway | Combined | Source |
|---|---|---|---|---|---|
| 3L 6-cyl · Automatic 10-spd · 4-Wheel Drive | DieselDiesel | 19 MPG | 20 MPG | 19 MPG | EPA #49417 |
Other 2026 GMC Sierra versions
EPA lists these versions separately. The figures above apply to the listing named “Sierra 4WD AT4X with Sport Mode”; they are not a specification for every Sierra trim.
What would it cost you to run?
Enter your own mileage and prices — these are assumptions, not live pump prices.
| Configuration | Annual cost | Calculation basis |
|---|---|---|
| 3L 6-cyl · Automatic 10-spd · 4-Wheel DriveEPA #49417 | $2,211 | Diesel operation |
Miles ÷ combined MPG × price per gallon; electric versions use miles ÷ 100 × kWh/100 miles × price per kWh. Plug-in hybrids show gasoline operation only. Maintenance, insurance and depreciation are excluded.
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See what the paid report includes →Use these specs to check a 2026 Sierra 4WD AT4X with Sport Mode listing
- Confirm the seller’s car is a 2026 GMC Sierra 4WD AT4X with Sport Mode with the Automatic 10-spd.
- Check that it takes Diesel on the vehicle’s own fuel label.
- Run the VIN for identity, title and reported history — none of which is in this EPA data.
- Check open recalls on the NHTSA lookup and have the car inspected.
Sources reviewed
Open the underlying public source and verify that its scope matches the question you are asking.
Frequently asked questions
What is the gas mileage of the 2026 GMC Sierra 4WD AT4X with Sport Mode?
The 2026 GMC Sierra 4WD AT4X with Sport Mode is rated 19 MPG combined by the EPA (19 city, 20 highway). That is 4% above the 18.3 MPG average across the 73 EPA configurations in the 2026 Standard Pickup Trucks 4WD class, placing it in the 65th percentile of its class. At 12,000 miles at $3.50/US gallon it costs about $2,211 a year to run.
What transmission does the 2026 GMC Sierra 4WD AT4X with Sport Mode have?
EPA records list Automatic 10-spd across the 1 rated configuration of the 2026 GMC Sierra 4WD AT4X with Sport Mode. These are model-level configurations. Match the individual car’s VIN and factory build information before identifying a replacement transmission.
What fuel does the 2026 GMC Sierra 4WD AT4X with Sport Mode use?
The 2026 GMC Sierra 4WD AT4X with Sport Mode is listed with Diesel. Match the particular configuration and follow the vehicle’s fuel label and owner’s manual.
How much does the 2026 GMC Sierra 4WD AT4X with Sport Mode cost to run per year?
About $2,211 in fuel or energy at 12,000 miles at $3.50/US gallon, using the 19 MPG combined EPA rating. That excludes maintenance, insurance, depreciation and charging-session fees. Enter your own mileage and prices in the calculator on this page for a figure that matches your driving.
Are these the exact specifications of my Sierra 4WD AT4X with Sport Mode?
These are the 1 EPA model-year configuration recorded for the 2026 GMC Sierra 4WD AT4X with Sport Mode, not a decode of an individual VIN or a complete trim catalogue. Confirm identity, installed equipment and service requirements with the car’s VIN and manufacturer records.
Will I achieve the listed fuel economy?
EPA ratings support comparisons under standardized test conditions. Your result depends on driving, weather, tyres, load, charging pattern and vehicle condition. The cost calculator uses the listed combined rating and your entered prices.