The 2021 GMC Sierra 4WD with the 5.3L V8 engine gets an estimated 19 MPG combined. This might not excite everyone, but it is what you can expect if you need a full-size, four-wheel-drive pickup. These trucks are for people who regularly tow boats, haul equipment, or drive on rough terrain. For them, fuel efficiency is less important than getting the job done.

City and highway performance

The EPA estimates the 2021 GMC Sierra 4WD 5.3L V8 gets 16 MPG in the city and 22 MPG on the highway. The lower city MPG isn’t surprising; stop-and-go traffic and idling use a lot of fuel in any large engine. The highway number is better, but it still shows the Sierra’s weight and shape. The 10-speed automatic transmission works hard to keep the engine running efficiently, but ultimately, moving a lot of truck needs fuel. Drivers who do a lot of highway driving will likely see their average MPG get closer to 22, since they will be spending more time on the open road.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 GMC Sierra 4WD 5.3L V8 at $2,300. This is based on driving 15,000 miles per year and using average national gas prices. Your actual costs will change depending on how you drive, local gas prices, and the type of gas you use. Driving hard and towing often will increase this cost. The EPA method lets consumers compare vehicles and estimate running costs.

Real-world expectations

EPA estimates are a starting point, but real-world MPG often varies. How you drive, how much weight you’re carrying, your tire pressure, and even the weather can all change fuel consumption. Quick acceleration, high speeds, and heavy loads will all lower your MPG. Owners who want better fuel efficiency should drive smoothly, keep their tires properly inflated, and not carry extra weight in the truck bed. Using Tow/Haul mode will also significantly reduce MPG, so only turn it on when you need it. See SIERRA MPG across all years to understand more.

How it compares

The 2021 GMC Sierra’s fuel economy is similar to other full-size, 4WD trucks. The Ford F-150 with its 5.0L V8 and 4WD gets about the same, around 19 MPG combined. Ram’s 1500, especially with the eTorque mild-hybrid system, can sometimes do a little better, getting around 20 MPG combined in similar versions. The Chevrolet Silverado, which is similar to the Sierra, has very similar MPG numbers. A Toyota Tundra usually gets less MPG than the domestic trucks, often around 15-17 MPG combined. Buyers in this class care more about what a truck can do than fuel, but they still pay attention to the differences between brands. Check all Gmc fuel economy data.

Tips to maximize efficiency

Minimize idling. The 5.3L V8 uses a lot of fuel when idling. Avoid idling for too long, especially when it’s cold. If you’re going to be stopped for more than a minute or two, turn off the engine.

Check and adjust tire pressure. Correct tire pressure lowers rolling resistance, which improves fuel economy. Check your tire pressure often and inflate tires to the pressure on the sticker on your door.

Use cruise control carefully. On fairly flat highways, cruise control can help you keep a steady speed and save fuel. But don’t use cruise control on hills or in stop-and-go traffic, as it can actually lower MPG in those situations. Let the 10-speed transmission work, and look ahead to avoid surprises.

Reduce weight. Extra weight lowers gas mileage. Remove any unnecessary items from the truck bed and cab. Even small objects add up and hurt MPG. A bed cover can lower drag and improve aerodynamics, which helps at highway speeds.

Service the truck regularly. Follow your truck’s maintenance schedule. An engine that is taken care of runs more efficiently. Change the oil and filter when you’re supposed to, and make sure the air filter is clean for the best airflow.