Seventeen MPG combined defines the 2025 GMC Sierra 4WD with the 2.7L turbocharged four-cylinder, a figure that, for many, immediately raises an eyebrow. This isn’t a light-duty, city-slicking pickup; it’s a full-sized, four-wheel-drive truck, engineered for capability, towing, and enduring the daily grind on construction sites or hauling weekend toys. The 17 MPG rating reflects the reality of moving nearly 5,000 pounds of steel, glass, and technology, with the added parasitic losses of a strong 4WD system, all while delivering a smooth, confident powerband. Buyers of this specific Sierra configuration aren’t chasing segment-leading efficiency, they’re prioritizing a manageable initial cost, a surprisingly stout engine package, and the unmatched utility of a half-ton pickup, willingly accepting a fuel economy number congruent with its workhorse mission.

City and highway performance

The EPA rates the 2.7L Sierra 4WD at 17 MPG in city driving and a mere 18 MPG on the highway. This near-identical split isn’t an anomaly, it speaks to the fundamental characteristics of a modern turbocharged engine paired with an eight-speed automatic in a heavy vehicle. In urban environments, stop-and-go driving invariably hits all vehicles hard, and the Sierra is no exception. While the turbocharger helps get it moving quickly from a standstill, the sheer mass and the transmission’s constant shifting to find the optimal gear for acceleration and deceleration keep the city number where it is. On the highway, the situation changes, but not dramatically enough to create a significant spread. The eight-speed transmission works diligently to keep revs low at cruising speeds, but the truck’s substantial frontal area and overall aerodynamic profile create considerable drag. There’s only so much a four-cylinder, even a powerful one, can do to overcome physics when pushing a box through the air at 70 mph. The engine is consistently working within its boost range, which, while providing ample power, consumes fuel. Drivers who spend most of their time on open interstates might observe a slight improvement over the 18 MPG highway estimate, but expecting mid-20s figures is unrealistic for this vehicle class and powertrain.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,600 for the 2025 GMC Sierra 4WD 2.7L. This figure is computed based on driving 15,000 miles per year, with an assumed mix of 45% highway and 55% city driving, using national average fuel prices. For a vehicle with a 17 MPG combined rating, this cost reflects the real-world expense of keeping it fueled for typical usage. It’s a direct, transparent calculation designed to give prospective buyers a clear understanding of one of the major recurring costs of ownership. While individual fuel prices and driving habits will always cause some fluctuation, this $2,600 baseline provides an accurate and representative financial expectation. It’s a sum that highlights the operational cost of owning a full-size, four-wheel-drive pickup, a cost that the target buyer has likely already factored into their budget.

Real-world expectations

Anticipate real-world fuel economy for the 2.7L Sierra 4WD to hover consistently around the EPA combined rating, perhaps dipping slightly below with a heavy foot or frequent towing. The engine’s character, a punchy, low-end torque delivery, encourages assertive driving, which directly impacts fuel consumption. Those who regularly tow small to mid-sized trailers, such as utility trailers, small campers, or ATVs, will see figures drop further, potentially into the low teens. The beauty of this 2.7L turbo isn’t its frugality but its unexpected power. It feels like a bigger engine, delivering V8-like torque off the line, which can be seductive. However, extracting that power means burning gasoline. Conversely, light-footed drivers who master smooth acceleration and gentle braking might occasionally nudge the highway number closer to 20 MPG, but it will require conscious effort. The key takeaway is that the EPA estimates are a reliable guide, don’t expect miracles, but don’t fear significant underperformance unless your driving habits are exceptionally aggressive or towing is a constant activity. For a deeper look into SIERRA MPG across all years, explore our complete data.

How it compares

Comparing the 2.7L Sierra 4WD’s 17 MPG combined with key rivals illuminates its standing. Ford’s F-150 with the 2.7L EcoBoost 4×4, for instance, typically achieves 19 MPG combined, splitting to 18 City/23 Highway. This difference primarily comes from Ford’s more aggressive use of a 10-speed transmission, which allows for finer gearing and often lower highway RPMs. RAM’s 1500 with the 3.6L V6 eTorque 4×4 often hits 21 MPG combined (19 City/24 Highway), demonstrating the lighter touch of a mild-hybrid system. Even the Silverado, functionally identical to the Sierra, will achieve the same numbers with the 2.7L turbo. The GMC buyer accepting 17 MPG isn’t cross-shopping based on ultimate efficiency, they’re valuing the Sierra’s specific cabin refinement, design aesthetics, and the proven capability of GM’s powertrain in a package that fits their budget and needs. The slightly lower MPG compared to some rivals is a known quantity for someone specifically drawn to the Sierra’s unique blend of ruggedness and premium feel without the often higher initial cost of a V8 or a more complex hybrid system. For detailed information on all Gmc fuel economy data, our platform offers a complete overview.

Tips to maximize efficiency

Maintaining consistent steady speeds, particularly on the highway, plays a significant role in improving the 2.7L Sierra’s fuel economy. Avoid unnecessary bursts of acceleration and heavy braking. Engaging the cruise control on open roads helps the 8-speed automatic maintain optimal engine RPMs, preventing wasteful fuel consumption from fluctuating throttle inputs.

Keep your tires properly inflated to the manufacturer’s recommended pressures. Underinflated tires increase rolling resistance, forcing the engine to work harder and directly impacting fuel economy. Refer to the sticker on your driver’s side door jamb for the correct PSI.

Minimize excess weight in the bed or cabin. While the Sierra is designed to carry substantial loads, hauling heavy, unneeded items constantly reduces efficiency. Every extra pound your engine has to move requires more fuel.

Plan your routes to avoid excessive stop-and-go traffic whenever possible. The 2.7L engine, like any turbocharged setup, uses more fuel to spool up the turbocharger and accelerate its mass from a standstill. Smooth, flowing traffic allows the engine to operate more efficiently.

Regular maintenance, including timely oil changes, air filter replacements, and spark plug checks, ensures the engine operates at peak efficiency. A well-maintained engine burns fuel more completely and effectively, directly contributing to better mileage.