The 2024 GMC Sierra 4WD AT4X with the 6.2L V8 gets 15 MPG combined. Of course, nobody buys this truck expecting Prius-like efficiency. It’s a purpose-built off-road machine, a luxury-trimmed bruiser designed for serious capability and a commanding presence, not for maximum gas mileage. AT4X buyers prioritize ground clearance, advanced dampers, and a throaty exhaust note over minimizing their carbon footprint.

City and highway performance

EPA estimates show a fairly narrow band of fuel economy between city and highway driving. Expect 14 MPG in urban environments, rising slightly to 16 MPG on the open road. This reflects the realities of a large-displacement engine hauling over 5,700 lbs, regardless of driving conditions. Stop-and-go traffic and aggressive acceleration will drag the city MPG lower. Consistent highway cruising might add a bit more, but don’t expect dramatic changes. The 10-speed automatic transmission helps optimize the engine’s output, but physics still apply.

Annual fuel cost

Budget accordingly, the EPA says the annual fuel cost for the 2024 GMC Sierra AT4X 6.2L is $3,850. This calculation is based on driving 15,000 miles per year and assuming national average fuel prices. Your fuel costs can vary significantly depending on your driving habits, local gasoline prices, and how often you drive off-road. AT4X buyers are unlikely to be deterred by this figure. The price of this capability and luxury includes a large fuel bill.

Real-world expectations

While the EPA estimates provide a benchmark, real-world fuel economy varies. Some owners report figures slightly below the official ratings, especially if they frequently use four-wheel drive, tow trailers, or live in hilly areas. The aggressive tires and raised suspension of the AT4X also increase aerodynamic drag, hurting fuel efficiency. Expect averages closer to 12-14 MPG in mixed driving. If you drive long highway stretches and try to save gas, you might match the EPA figure, but that’s not what this truck is for.

How it compares

The Sierra AT4X’s fuel economy is low for the full-size truck segment, particularly among those with V8 engines and four-wheel drive. For example, a Ford F-150 Raptor, with more horsepower from its EcoBoost V6, gets a slightly better 15 MPG combined. A Ram 1500 TRX, with its supercharged Hemi V8, gets the same 12 mpg city, 15 mpg combined. Even mainstream V8-powered trucks like the Chevrolet Silverado 1500 with the 6.2L manage slightly better (around 16-17 MPG combined), though not by much. Fuel economy is not a strength for any serious off-road truck. For a broader view, check out all GMC fuel economy data.

Tips to maximize efficiency

The 6.2L V8 uses a lot of gas, so maximizing fuel economy takes work. Avoid aggressive acceleration and hard braking. This engine does better with a smooth and steady driving style. Predict traffic flow and coast whenever possible to reduce the need to accelerate.

Tire pressure is critical, especially for a heavy truck with aggressive tires. Inflate your tires to the recommended pressure to reduce rolling resistance. Check and adjust pressure regularly, as it changes with temperature.

Minimize weight in the bed. Extra cargo adds strain on the engine and reduces fuel economy. Remove items you don’t need for daily drives, and consider a lightweight bed cover to improve aerodynamics.

Use the available drive modes carefully. When not off-roading, select two-wheel-drive to reduce drivetrain drag. Four-wheel-drive consumes more fuel, so only engage it when you need traction. Exploring SIERRA MPG across all years can also provide insight into long-term trends.

Keep up with regular maintenance for a more efficient engine. Follow the manufacturer’s service schedule for oil changes, air filter replacements, and spark plug maintenance.