25 MPG combined. That’s the headline figure for the 2024 GMC Sierra 2WD equipped with the Duramax 3.0L inline-six diesel, and it’s a number that will appeal to truck buyers who want real-world towing capability and long-distance cruising. This isn’t the Sierra for the casual weekend warrior; it’s the Sierra for the rancher hauling cattle, the contractor transporting equipment, and anyone else who routinely needs a half-ton truck’s capabilities without constantly wincing at the pump.

City and highway performance

The EPA estimates the Sierra diesel at 23 MPG in the city and a more impressive 29 MPG on the highway. The city figure reflects stop-and-go driving, where the diesel engine’s efficiency is somewhat diminished. However, the highway figure highlights the engine’s strengths. At steady cruising speeds, the Duramax sips fuel, making it a long-haul champ. This allows owners to confidently rack up highway miles without constant fuel stops. The 10-speed automatic transmission also deserves credit here, keeping the engine in its optimal efficiency range.

Annual fuel cost

According to the EPA, the estimated annual fuel cost for this configuration is $2,250. This figure is based on 15,000 miles of driving per year, with fuel prices reflecting a national average. This cost provides a benchmark for comparing its fuel costs against other vehicle options, but individual spending will fluctuate based on driving habits and local fuel prices.

Real-world expectations

EPA estimates offer a baseline, but the actual fuel economy you achieve will depend heavily on how you use your Sierra. Towing significantly degrades fuel economy, as does aggressive driving. However, owners who prioritize smooth acceleration, anticipate traffic, and minimize idling can often meet or even exceed the EPA estimates, especially on longer highway drives. The Duramax delivers consistent fuel economy in real-world conditions, which is partly why it is so popular.

How it compares

Compared to gasoline-powered full-size trucks, the Sierra’s diesel offers a clear advantage in fuel economy, particularly on the highway. For example, a 2024 Ford F-150 2WD with the 2.7L EcoBoost V6 is rated at 20 MPG combined. The Ram 1500 2WD with the eTorque 3.6L V6 comes in at 22 MPG combined. These numbers highlight the diesel’s competitive edge. Across the SIERRA MPG across all years, the diesel consistently offers better fuel economy. Even when comparing to hybrid options, this diesel Sierra remains a strong contender due to its superior towing capabilities, making it the clear choice for those who need both less gas and hard-working performance. Owners should always consult all Gmc fuel economy data for the most complete picture.

Tips to maximize efficiency

The Duramax diesel responds well to smooth and deliberate driving. Avoid sudden acceleration and braking, which can quickly drain fuel. Instead, gradually build speed and anticipate traffic flow to maintain momentum.

Tire pressure plays a critical role in fuel economy. Ensure that your Sierra’s tires are inflated to the recommended pressure, which can be found on the doorjamb sticker. Underinflated tires create more rolling resistance, which increases fuel consumption.

Reduce unnecessary weight. Hauling extra cargo, even if it’s within the truck’s payload capacity, will negatively impact fuel economy. Only carry what you need for the task at hand, and remove any unnecessary items from the bed of the truck.

Pay attention to maintenance. Regular oil changes, air filter replacements, and proper vehicle maintenance all contribute to optimal fuel efficiency. A well-maintained engine runs more smoothly and efficiently, saving you money at the pump.

Minimize idling. Diesel engines are generally more efficient than gasoline engines at idling, but excessive idling still wastes fuel. If you’re going to be stopped for more than a minute or two, it’s generally more fuel-efficient to turn off the engine.