17 MPG combined is what buyers of the 2020 GMC Sierra 2WD with the 4.3L V6 can expect. This isn’t a number that will win any fuel efficiency awards, but it’s the price of admission for a work-focused, half-ton truck that prioritizes capability and affordability over saving fuel. This Sierra configuration isn’t trying to be green; it’s designed to be a reliable workhorse for contractors, small business owners, or anyone who needs a truck bed and towing capacity on a budget. They know what they’re getting.

City and highway performance

The EPA estimates place city driving at 16 MPG and highway runs at 21 MPG. The city number reflects the stop-and-go nature of urban environments, where the 4.3L V6 and 6-speed automatic transmission work harder to get the Sierra moving from a standstill. The highway figure, though slightly better, still reveals that the Sierra’s aerodynamics aren’t its strong suit. The tall, boxy profile contributes to wind resistance at higher speeds, impacting fuel consumption. This difference between city and highway also highlights the truck’s behavior under different loads; it performs comparably between the two when not hauling or towing.

Annual fuel cost

The EPA estimates the annual fuel cost for the 2020 GMC Sierra 2WD 4.3L V6 at $2,600. This figure is based on driving 15,000 miles per year, with fuel prices reflecting a national average. Individual costs could vary significantly depending on local gas prices and driving habits. It’s a benchmark though a quick way to gauge relative fuel expenses when shopping for a truck. For someone driving more than 15,000 miles annually, or who lives in an area with higher fuel costs, the annual expenditure on gasoline will climb accordingly. This is a critical factor for buyers planning to use the Sierra for commercial purposes.

Real-world expectations

While the EPA estimates offer a standardized benchmark, real-world MPG often deviates. Driving style, terrain, and the load in the bed or while towing a trailer all play a significant role. Expect to see figures close to the EPA estimates under ideal conditions relatively flat roads, consistent speeds, and minimal cargo. Aggressive acceleration, frequent braking, and hauling heavy loads will quickly drop the MPG. Owners who prioritize fuel conservation and drive with a light foot can potentially match or even slightly exceed the EPA estimates, but those with a lead foot will likely see lower numbers. Take a look at SIERRA MPG across all years to see what owners report.

How it compares

Compared to other full-size trucks of the same era, the 2020 GMC Sierra 2WD 4.3L V6’s fuel economy lags behind some more modern, fuel-efficient powertrains. For instance, the Ford F-150 with the 2.7L EcoBoost V6 achieves a combined 22 MPG in 2WD configuration, offering a significant improvement. Even the Ram 1500, known for its comfort and ride quality, can achieve around 20 MPG combined with its V6 eTorque engine. However, these more efficient options often come at a higher price point. Within GMC’s own lineup, the more powerful 5.3L V8 in the Sierra achieves nearly identical MPG numbers. This comparison matters because buyers on a budget might find the fuel savings from a more expensive, more efficient truck offset by the higher initial cost. Plus you can explore all Gmc fuel economy data from other models.

Tips to maximize efficiency

Avoid aggressive acceleration and hard braking. The 4.3L V6 responds well to smooth, steady inputs. Anticipate traffic flow, maintain a consistent speed, and allow the truck to coast whenever possible to reduce fuel consumption. Slamming on the gas and then immediately hitting the brakes is the fastest way to burn through fuel.

Regular maintenance is important. Ensure the tires are properly inflated to the recommended pressure, the engine air filter is clean, and the engine oil is fresh. A well-maintained engine will run more efficiently and deliver better fuel economy. Small things like infrequent oil changes can quickly diminish MPG.

Minimize payload weight. The 4.3L V6 has to work harder to move heavier loads. If you’re not actively using items in the truck bed or cab, remove them. Extra weight adds unnecessary strain on the engine and reduces fuel efficiency. Every pound counts.

When possible, avoid idling for extended periods. If you’re stopped for more than a minute or two, turn off the engine. Idling consumes fuel without moving the truck forward. This is especially important in urban environments with frequent stops.

Use cruise control on the highway. Maintaining a consistent speed on long highway drives can help optimize fuel efficiency. Cruise control minimizes speed fluctuations, which can improve MPG. Setting cruise control conservatively can give a significant MPG boost during longer trips.