The 2021 GMC Sierra 4WD with the 4.3L V6 engine gets 17 MPG combined. This isn’t a chart-topping figure, but it’s important to consider the Sierra’s purpose: a work truck designed for hauling, purchased more for its utility than its fuel efficiency. Fleet buyers, contractors, and those needing a truck bed and a strong powertrain often favor this configuration, even if it doesn’t have all the latest features or the highest MPG.

City and highway performance

The EPA estimates the 2021 GMC Sierra 4WD 4.3L V6 gets 15 MPG in the city and 20 MPG on the highway. The city MPG reflects the frequent stops in urban driving, where the truck’s weight and traditional six-speed automatic transmission reduce fuel efficiency. On the highway, maintaining a steady speed can achieve the estimated 20 MPG. The 4.3L V6 isn’t the most advanced engine in the Sierra lineup, but it’s a proven workhorse, known for its reliability and enough power for everyday tasks. Remember that EPA estimates are based on ideal conditions, and real-world fuel economy depends on driving style, cargo weight, and terrain.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2021 GMC Sierra 4WD 4.3L V6 at $2,600. This is based on driving 15,000 miles per year and national average fuel prices. Your actual fuel costs depend on your mileage, driving type (city or highway), and local fuel prices. This cost can be a major factor for fleet managers and those on a budget, so consider your driving habits before buying this truck.

Real-world expectations

While the EPA provides a standard estimate, actual fuel economy for the 2021 GMC Sierra 4WD 4.3L V6 varies widely. Drivers who frequently tow heavy loads or drive in stop-and-go traffic will likely see lower MPG than the EPA estimates. But, those mainly doing highway driving and practicing efficient driving habits could achieve numbers closer to the 20 MPG highway rating. Online forums and fuel tracking apps often show a range of MPG figures for this configuration, so manage your expectations accordingly.

How it compares

The 2021 GMC Sierra 4WD 4.3L V6 is near the lower end of the fuel economy range compared to other full-size trucks. A 2021 Ford F-150 with the base 3.3L V6 and 4WD gets a slightly better 19 MPG combined. The updated 2.7L turbo four-cylinder in the F-150 gets 20 MPG combined with 4WD. The RAM 1500 with the eTorque 3.6L V6 also performs well, offering 21 MPG combined with 4WD due to its mild-hybrid system. These small fuel economy differences can add up over a year, especially for high-mileage drivers. Some buyers may value the Sierra’s proven V6, simplicity, and lower initial price despite the slight fuel economy disadvantage. If you’re shopping within the Sierra family, checking SIERRA MPG across all years can also reveal some surprises. For a broader view, take a look at all Gmc fuel economy data.

Tips to maximize efficiency

One way to improve fuel economy in the 2021 GMC Sierra 4WD 4.3L V6 is to reduce weight. Remove unnecessary items from the truck bed and cab. Extra weight requires the engine to work harder, consuming more fuel. This is especially important for those who use their Sierra for work, where tools and equipment can quickly add up.

Aggressive acceleration and hard braking decrease fuel economy. Accelerate gradually and anticipate traffic to maintain a consistent speed and reduce sudden stops. A light touch on the accelerator means fewer trips to the gas station.

Correct tire inflation is important for maximizing fuel efficiency. Regularly check your tires and inflate them to the recommended pressure on the doorjamb sticker. Underinflated tires create more rolling resistance, making the engine work harder and decreasing MPG. Even a few PSI below the recommended level can affect fuel economy.

Avoid using four-wheel drive on paved roads. Using 4WD increases fuel consumption due to the added mechanical resistance and weight. Only use 4WD when necessary, such as on slippery or unpaved surfaces. Keeping it in 2WD on dry roads improves fuel economy.