The gas mileage of a Chevy Silverado 2500HD will vary based on factors like the equipped powertrain, driving habits, road conditions, and more. The Chevy Silverado 2500 HD is exempt from EPA fuel-economy testing. That said, third-party testing by Car and Driver showed that a 2022 Chevy Silverado equipped with a 6.6-liter V-8 engine and 10-speed automatic transmission delivered 14 mpg on the highway3.