The 2017 GMC Sierra C15 with the 6.2L V8 and rear-wheel drive gets 17 MPG combined. Anyone shopping for this Sierra configuration likely isn’t prioritizing fuel efficiency. This isn’t a commuter truck; it’s a statement, a workhorse for those who prioritize V8 power and towing capacity over maximizing trips between fuel stops, or those who simply enjoy the rumble and responsiveness of a powerful, naturally aspirated engine. This truck is bought by those who need to haul, tow, or simply want a capable pickup with a muscular presence. People buy this truck for its capability and personality and are willing to accept the fuel consumption that comes with it.

City and highway performance

The official EPA numbers break down to 15 MPG in the city and 21 MPG on the highway. The city number reflects the engine working hard, constantly accelerating from stops and idling in traffic, where the 6.2L’s displacement becomes a disadvantage. The highway figure of 21 MPG is more palatable, achievable when cruising at a steady speed. The 8-speed automatic transmission helps here, keeping the engine in the lower end of its RPM range when appropriate. However, even on the highway, a heavy foot will quickly negate any potential fuel savings.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,600 for this Sierra configuration. This figure is based on driving 15,000 miles per year, using a national average fuel price. Keep in mind this is an average, if you drive more than 15,000 miles annually, or if fuel prices are higher in your location, your actual costs will be significantly higher. This $2,600 figure also doesn’t account for variations in driving style. Aggressive acceleration or frequent towing will worsen fuel economy and increase your yearly fuel bill.

Real-world expectations

While the EPA provides a standardized estimate, real-world fuel economy can vary substantially. If you frequently use the truck for towing or heavy hauling, expect to see numbers slightly below the EPA estimates. If you primarily use it for light-duty tasks and spend a considerable amount of time on the highway, you might approach or even slightly exceed the EPA’s 21 MPG highway rating. The Sierra’s trip computer can provide a useful indication of your average fuel economy, allowing you to monitor your driving habits and make adjustments.

How it compares

Compared to other full-size trucks with powerful engines, the 2017 Sierra C15’s fuel economy is generally in line with expectations. A similarly equipped Ford F-150 with the 5.0L V8 offers comparable, but perhaps slightly better, fuel economy, around 16 MPG combined. The RAM 1500 with the 5.7L Hemi lands in a similar range. The key takeaway is that none of these trucks are fuel misers when equipped with their most powerful engines. Someone cross-shopping these trucks isn’t prioritizing fuel economy above all else; they’re looking for capability and performance and are willing to accept the resulting fuel costs. If you’re willing to step down to a smaller engine, like the Sierra’s 5.3L V8 or a turbocharged V6 in a competitor, you’ll see a noticeable improvement. For example, a 2017 Sierra with the 5.3L is rated at 19 MPG combined. You can also check the SIERRA MPG across all years.

Tips to maximize efficiency

The Sierra’s 6.2L V8 responds well to smooth and deliberate throttle inputs. Avoid aggressive acceleration and hard braking, as these actions consume excessive fuel. Anticipate traffic flow and try to maintain a consistent speed to optimize fuel economy. Using cruise control on the highway can help maintain a steady pace, although the system can sometimes be slow to react, resulting in dips in gas mileage when driving through hilly terrain.

Regular maintenance is essential for optimal fuel economy. Ensure your tires are properly inflated to the recommended pressure, as underinflated tires increase rolling resistance and reduce efficiency. Also, keep up with scheduled oil changes and air filter replacements. Using the correct grade of oil is key to keeping the engine lubricated and therefore efficient.

Minimize unnecessary weight. The Sierra is a heavy truck to begin with, so avoid carrying around items in the bed or cabin that you don’t need. Removing extra weight reduces the load on the engine and improves fuel economy, especially in city driving. This also means emptying out any tools and equipment that may be in the vehicle but not needed.

Consider using the Sierra’s Tow/Haul mode only when necessary. While it’s designed to improve performance when towing or carrying heavy loads, it can negatively impact fuel economy when used in normal driving conditions. The Tow/Haul mode alters the shift points of the transmission to provide you with better access to the engine’s power band and therefore reduce the need for downshifting. Make sure to browse all Gmc fuel economy data.