The official EPA fuel economy rating for the 2021 GMC Sierra 2WD with the 2.7L turbocharged four-cylinder engine is 21 MPG combined. While this isn’t going to win any awards for low fuel costs, especially compared to hybrid cars, it’s a real achievement for a full-size pickup truck designed for work and occasional heavy hauling. This Sierra configuration is for a specific buyer: someone who needs a truck bed and the size of a Sierra, but doesn’t require V8 power or 4×4 for daily driving.

City and highway performance

EPA estimates are 20 MPG in the city and 23 MPG on the highway. This highlights where the 2.7L turbo shines and where it has limitations. The city figure shows the engine’s strong low-end torque, which allows it to accelerate from stoplights without using too much gas. The eight-speed automatic transmission also helps by keeping the engine in its best operating range. However, the highway figure shows that even a turbocharged four-cylinder has to work harder to move a large, heavy truck at high speeds. Aerodynamic drag becomes more important above 70 MPH, which affects fuel consumption.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 GMC Sierra 2WD 2.7L at exactly $2,100. This is based on driving 15,000 miles per year, using a weighted average of city and highway MPG, and assuming the national average fuel price. Individual fuel costs will vary depending on driving habits and local gas prices. If you drive more than 15,000 miles annually, or if gas prices are higher in your area, expect to pay more. If you drive fewer miles, your expenses will be less.

Real-world expectations

The EPA provides a standard, but real-world fuel economy varies. Aggressive driving, frequent towing, heavy loads, and even tire pressure can all change your MPG. Owners of this Sierra often get figures close to the EPA estimates when driven responsibly. However, pushing the truck hard or using it for short trips in stop-and-go traffic will result in lower numbers. Weather can also be a factor, cold temperatures often reduce fuel economy because of increased engine friction and winter-blend gasoline.

How it compares

When considering fuel economy, compare the Sierra 2.7L to its competitors. The Ford F-150 with its 2.7L EcoBoost V6 usually gets around 20 MPG combined in 2WD configuration, that’s comparable. The RAM 1500 with the eTorque 3.6L V6 often gets around 22-23 MPG combined, a slight advantage. The Chevrolet Silverado, similar to the Sierra, returns nearly identical figures with its 2.7L turbo. These differences are important to a very specific buyer. Someone downsizing from a V8 or considering a more fuel-efficient work truck may cross-shop these models, paying attention to how their real-world driving matches up to the official EPA ratings. You can view all Gmc fuel economy data at FuelEconomyHub.

Tips to maximize efficiency

Lighten the load. The 2.7L turbo works efficiently when it doesn’t have to strain, so avoid carrying unnecessary weight in the bed. Every extra hundred pounds reduces MPG, particularly in city driving. Only carry what you need.

Smooth and steady wins the race. This engine gets its best fuel economy with gentle acceleration and consistent speeds. Avoid sudden bursts of acceleration or hard braking, because these actions consume more fuel. Anticipate traffic flow and maintain a steady pace whenever possible. Don’t be afraid to let the transmission do its work.

Maintain proper tire pressure. Underinflated tires increase rolling resistance, which decreases fuel economy and tire life. Check your tire pressure regularly and inflate them to the recommended pressure on the doorjamb sticker. This is a simple way to improve fuel efficiency.

Remember the maintenance schedule. Regular maintenance, including oil changes, air filter replacements, and spark plug inspections, ensures that your engine runs efficiently. A well-maintained engine consumes less fuel and performs better. Consult your owner’s manual for the recommended maintenance schedule. If you want to know more about SIERRA MPG across all years and configurations be sure to check out all the data we provide on FuelEconomyHub.