15 MPG combined might seem low, but for the 2020 GMC Sierra Cab Chassis 2WD equipped with the 5.3L V8, it’s an expected trade-off. This truck isn’t designed for Prius-like efficiency. It’s a workhorse, a platform chosen for its reliable frame, payload capacity, and suitability for upfitting into tow trucks or landscape vehicles. Fuel economy is a consideration, but capability and durability are more important.

City and highway performance

The EPA estimates the 2020 GMC Sierra Cab Chassis 2WD 5.3L V8 gets 14 MPG in the city and 18 MPG on the highway. This difference reflects typical driving conditions. Stop-and-go city driving, idling at job sites, and frequent acceleration with heavy loads all increase fuel consumption. The highway number, while better, is still lower than lighter-duty pickups due to the cab chassis’ heavier construction and less aerodynamic shape. The 6-speed automatic transmission, while durable, also lacks the fuel-saving benefits of the 8- or 10-speed automatics found in newer trucks. These numbers reflect the trade-offs in a vehicle designed for hard work, not fuel efficiency.

Annual fuel cost

The EPA estimates an annual fuel cost of $2,900 for the 2020 GMC Sierra Cab Chassis 2WD. This is based on driving 15,000 miles per year, using an estimated fuel price calculated from national averages. Your individual fuel costs may vary, depending on how many miles you drive and how much you pay per gallon. Those who primarily use this truck for short-distance work or infrequent long hauls will likely spend less than $2,900 annually. Owners who consistently rack up high mileage or operate in areas with higher fuel prices could easily exceed that figure.

Real-world expectations

While the EPA provides a standardized benchmark, real-world fuel economy can vary significantly based on load weight, which is a major factor. The more you haul, the more fuel you’ll burn. Driving style also matters. Aggressive acceleration and hard braking reduce fuel economy, but smoother driving habits will improve it. Terrain also affects fuel consumption. Driving in hilly or mountainous areas will increase it compared to flat terrain. Given the likely usage scenarios for this vehicle, expect the MPG to be potentially lower than the EPA estimates, especially when operating with substantial payloads. You may find all Gmc fuel economy data interesting when looking at the efficiency across the entire fleet of vehicles.

How it compares

Compared to other cab chassis trucks, the 2020 GMC Sierra 2WD’s fuel economy is generally similar to its competitors. The Ford F-350 XL Cab Chassis, for example, equipped with its standard 6.2L V8, achieves roughly similar MPG ratings, and the RAM 3500 Tradesman Cab Chassis similarly offers similar MPG estimates from its gasoline powertrains depending on the specific configuration. If you need a cab chassis truck, you’re unlikely to find a much more fuel-efficient alternative with similar capabilities. Efficiency gains usually come with a reduction in towing capacity, payload capacity, or both. Always compare SIERRA MPG across all years when making a vehicle decision.

Tips to maximize efficiency

Regular maintenance is critical for maximizing fuel economy in any vehicle, especially a heavy-duty work truck. Ensure the engine is properly tuned, the tires are correctly inflated, and the air filter is clean. Neglecting these simple tasks can significantly reduce fuel efficiency.

Minimize idling. While necessary in some situations, prolonged idling wastes fuel and increases emissions. If you anticipate being stationary for more than a few minutes, shut off the engine. Given the nature of this vehicle’s work environment this rule may often be broken, but should be top of mind when considering fuel usage.

Drive smoothly and anticipate traffic conditions. Avoid aggressive acceleration and hard braking, as these habits consume excess fuel. Maintain a steady speed on the highway and anticipate upcoming traffic to avoid unnecessary stops and starts. The 6-speed will shift smoother when it does not have to compensate for rushed throttle.

Consider the weight of your load and distribute it evenly. Overloading the truck or unevenly distributing the weight can negatively impact fuel economy and handling. Ensure you are within the vehicle’s weight limits and that the load is properly secured.

If your use case allows, consider alternative fuel options if available and compatible. Some upfitters offer conversions to run on propane or compressed natural gas (CNG), which may offer lower operating costs and reduced emissions, although the initial investment can be significant.