The 2018 GMC Sierra C15 Cab Chassis 2WD with the 5.3L V8 gets 17 MPG combined. This fuel economy reflects a trade-off, as customers who upfit this truck with service bodies, dump bodies, or ambulance packages likely prioritize capability over efficiency. It’s a workhorse, and its fuel consumption reflects its purpose.

City and highway performance

The EPA estimates the Sierra C15 Cab Chassis 2WD gets 15 MPG in the city and 20 MPG on the highway. The 5.3L V8, working with a 6-speed automatic transmission, delivers plenty of power for hauling and towing. Stop-and-go traffic will decrease fuel mileage; however, highway driving can improve it at steady speeds.

Annual fuel cost

The EPA estimates the annual fuel cost at $2,600 for this Sierra configuration. This is calculated using 15,000 miles per year, with 55% city and 45% highway driving, based on national average fuel prices at the time. Keep in mind that variables like local fuel costs, driving habits, and the balance of city to highway miles can greatly change how much you spend on fuel.

Real-world expectations

Actual fuel economy will likely differ from the EPA estimates. Factors like payload, towing, and the weight of upfits all reduce fuel efficiency. Frequent stops, construction sites, and long periods of idling can lower the average mileage. Fuel costs are often included in the cost of doing business for these vehicles used in specific jobs.

How it compares

The 2018 Sierra C15 Cab Chassis with the 5.3L offers fuel economy in line with other similar work trucks. A 2018 Ford F-150 XL Regular Cab 2WD with the 5.0L V8 gets slightly better fuel economy at 19 MPG combined. A Ram 1500 Tradesman Regular Cab 2WD with the 5.7L Hemi V8 gets 17 MPG combined, with a lower 13 MPG city compared to the Sierra’s 15 MPG. These small MPG differences can add up, especially with changing fuel costs, but the purchase decision often comes down to more than just fuel economy. For example, fleet managers may look at all Gmc fuel economy data to find the best option across their whole fleet, or they may look at SIERRA MPG across all years to inform a long-term purchasing plan.

Tips to maximize efficiency

Don’t idle the engine unnecessarily. Idling wastes fuel without moving the vehicle. Shut off the engine if you expect to be stopped for more than a minute, especially on job sites or in waiting areas.

Keep tires properly inflated. Underinflated tires increase rolling resistance, which makes the engine work harder and use more fuel. Regularly check the tire pressure and inflate them to the levels listed on the door jamb sticker.

Drive smoothly. Avoid rapid acceleration and hard braking because both use extra fuel. Allow plenty of space between vehicles and anticipate traffic flow. Driving with gradual acceleration and gentle braking improves fuel economy.

Reduce weight. Remove any tools or equipment you don’t need from the vehicle. Extra weight increases fuel consumption. Keeping the truck as light as possible, while still meeting operational requirements, will save fuel over time.

Scheduled maintenance matters. Regular oil changes, replacing the air filter, and keeping the engine properly tuned can improve overall fuel economy and performance.