17 MPG combined is what you can expect from a 2021 GMC Sierra 2WD with the 5.3L V8 and six-speed automatic. This isn’t an economy car; it’s a light-duty pickup truck designed for hauling, towing, and a comfortable ride. The fuel economy is traded by owners who prioritize capability and power, buyers who need a truck for work or recreation and appreciate the Sierra’s blend of traditional truck values and modern features.

City and highway performance

The EPA estimates for the 2021 GMC Sierra 2WD with the 5.3L V8 aren’t particularly inspiring. 15 MPG in the city reflects stop-and-go traffic and the inefficiency of a large engine moving a heavy vehicle. The six-speed transmission, while proven and reliable, doesn’t offer the fuel-saving benefits of newer 8- or 10-speed units.

On the highway, expect around 21 MPG if you maintain a steady speed and avoid aggressive acceleration. Remember these are averages; your results will vary based on driving style, load, and terrain. Drivers constantly towing or hauling heavy loads will see considerably lower figures.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 GMC Sierra 2WD 5.3L V8 is approximately $2,600. This is calculated based on driving 15,000 miles per year with a mix of city and highway driving, using the national average fuel price. Fuel prices fluctuate, and your driving habits will impact this cost.

If you drive significantly more than 15,000 miles annually, or regularly experience higher-than-average fuel prices, expect to spend more. The $2,600 figure provides a reasonable baseline, but be prepared for variations.

Real-world expectations

While the EPA estimates offer a standardized benchmark, real-world fuel economy often differs. Drivers of the 2021 GMC Sierra 2WD 5.3L V8 report a range of experiences, with some struggling to meet the EPA estimates in mixed driving conditions. Factors such as frequent short trips, idling in traffic, and aggressive driving habits can reduce fuel efficiency. On the other hand, drivers who adopt a more conservative driving style, prioritize highway miles, and maintain their vehicles properly may see figures closer to, or even slightly exceeding, the EPA estimates. Your personal results are contingent on a variety of factors.

How it compares

Compared to other full-size trucks, the 2021 GMC Sierra 2WD 5.3L V8 sits in the middle of the pack in terms of fuel economy. The Ford F-150, particularly with its 2.7L EcoBoost V6, often achieves slightly better numbers, typically around 20 MPG combined. The Chevrolet Silverado, mechanically similar to the Sierra but sometimes with slightly different tuning, posts comparable numbers. Ram 1500 models with the eTorque mild-hybrid system can also offer a small advantage, particularly in city driving. For those seeking less gas consumption, the turbo-4 engine with 8-speed auto provides better fuel consumption.

However, buyers drawn to the Sierra 5.3L often prioritize the traditional feel and sound of a V8, trading some efficiency for proven performance and a specific driving experience. For all Gmc fuel economy data, check out our page on all GMC models. You can review SIERRA MPG across all years too.

Tips to maximize efficiency

Avoid aggressive acceleration and braking. The 5.3L V8 delivers ample power, but using it excessively burns unnecessary fuel. Gentle starts and smooth stops will make a difference over time. Anticipate traffic flow and maintain a steady speed when possible.

Keep your tires properly inflated. Underinflated tires increase rolling resistance, which forces the engine to work harder and consume more fuel. Check your tire pressure regularly and maintain it at the recommended level, typically found on a sticker inside the driver’s side doorjamb.

Minimize idling. Idling burns fuel without covering any distance. If you anticipate being stopped for more than a minute or two, turn off the engine. Restarting the engine consumes less fuel than idling for an extended period.

Reduce aerodynamic drag. Remove any unnecessary items from the truck bed or roof rack that increase wind resistance. A tonneau cover can also help to improve aerodynamics and potentially boost fuel economy, especially at highway speeds.

Consider fuel additives. The 5.3L V8 is a strong engine, but using a quality fuel additive periodically can help to keep the fuel system clean and optimize combustion, potentially leading to a slight improvement in fuel efficiency.