How many miles per gallon does a Chevy 2500 6.6 diesel get?

In most cases, the Chevrolet Silverado 2500HD with the 6.6-liter Duramax diesel gets roughly 15 miles per gallon in the city and about 20–21 mpg on the highway for 2WD models, with 4x4 versions typically a bit lower. Actual results vary based on weight, towing, terrain, and driving style.

What influences fuel economy in heavy-duty diesels

Fuel economy in a heavy-duty diesel pickup is shaped by payload, towing loads, driving speed, terrain, climate, and maintenance. Diesel engines excel at sustained torque at low RPMs, but towing heavy trailers or hauling payload increases fuel consumption significantly. Transmission choice and axle gear ratios also play a role in overall efficiency.

EPA fuel economy ratings

Official EPA estimates provide a baseline for comparing configurations. The figures below reflect typical ranges for the current Duramax-powered 2500HD pickups.

Two-wheel drive vs. four-wheel drive

EPA numbers differ slightly by drivetrain, with 2WD generally offering the best highway efficiency and 4x4 incurring a small penalty due to additional drivetrain components.

• 2WD Duramax 6.6L with 10-speed Allison: about 15 mpg city, 21 mpg highway, 17 mpg combined.


• 4x4 Duramax 6.6L with 10-speed Allison: about 15 mpg city, 20 mpg highway, 17 mpg combined.

Note: Exact figures vary by model year, cab/bed configuration, and other options. Always check the window sticker for the specific truck you’re considering.

Real-world fuel economy

Owner experiences and independent tests often show variations from the EPA numbers, especially under towing or heavy payload. The following ranges reflect typical real-world results observed by drivers and reviewers.

• Unloaded highway driving: approximately 18–22 mpg, depending on speed, aero efficiency, and engine load.


• Highway driving with light towing or payload: roughly 14–18 mpg.


• City driving with frequent stops or heavy payload: often 12–16 mpg.

In practice, diesel HD trucks like the 6.6L Duramax can deliver strong highway efficiency when not towing, but heavy-duty work—towing, plowing, or hauling—will reduce mpg noticeably.

Factors that can improve or degrade mpg

Maintenance, tire condition and inflation, aerodynamics (cargo, bed covers), and driving habits (steady speeds, gradual acceleration) can all swing fuel economy either up or down. Upgrades like proper exhaust systems or weight reductions may offer marginal gains, while towing with improper ballast or aggressive driving can dramatically reduce efficiency.

What to consider when shopping

If mpg is a priority, consider the drivetrain choice, typical load, and your planned usage. For highway-focused use with occasional towing, the 2WD configuration generally provides the best efficiency. For frequent towing or challenging terrain, the 4x4 model’s extra capability may justify the mpg trade-off.

Summary

The Chevrolet Silverado 2500HD with the 6.6L Duramax diesel typically delivers about 15 mpg in city driving and around 20–21 mpg on the highway for 2WD versions; 4x4 configurations usually fall slightly lower, around 15 mpg city and 20 mpg highway. Real-world results vary widely depending on payload, towing, terrain, and driving style. Checking the EPA window sticker for the exact year and configuration remains the best way to know your expected fuel economy, and practical testing based on your daily use will provide the most relevant figure.

What fuel mileage does a 6.6 l Duramax diesel get?

The 6.6L Duramax engine's MPG varies, but typically ranges from 15-18 MPG for mixed driving and 17-20 MPG for unloaded highway driving. Actual mileage depends heavily on factors like driving conditions, towing, and the specific model year. Some newer models achieve higher efficiency, with a 2025 Silverado HD hitting 20.4 MPG on a controlled highway loop. 
This video shows a fuel economy test of a 2021 Chevy Silverado HD with the 6.6L Duramax engine towing a trailer: 48struckguyjoeYouTube · Jan 15, 2021
Mileage breakdown by driving type: 
This video demonstrates a fuel economy test of a 2024 Chevy Silverado HD Duramax: 57sDaily MotorYouTube · Jun 27, 2023

• Mixed/City: Around 15 MPG or lower, especially with stop-and-go traffic. 
• Highway (unloaded): Typically 17-20 MPG, but can vary with speed. 
• Towing: Expect significantly lower mileage, often in the 10-14 MPG range depending on the load and terrain. 

Factors that influence MPG:

• Towing and load: Hauling heavy loads reduces fuel efficiency. 
• Driving conditions: Hilly terrain or stop-and-go city traffic lowers MPG. 
• Vehicle age and break-in: Newer trucks may improve after an initial break-in period, with some owners reporting increased mileage after a few thousand miles. 
• Other factors: Speed, road conditions, and factors like the truck's emissions system (e.g., temporary DPF regen cycles) can also have an effect. 

You can watch this video to see real-world mileage results for a 2022 GMC Sierra 2500 Duramax: 1mDaily MotorYouTube · Mar 26, 2022

How many miles per gallon does a Chevy Silverado 2500 6.6 get?

The Chevy Silverado 2500 with the 6.6 gas engine gets an average of approximately 13-17 mpg combined, but this varies significantly by model year, trim, and driving conditions. For example, a 2024 model might achieve 16-18 mpg city / 18-21 mpg highway in base trims like the Work Truck or Custom, while higher trims might be slightly lower, and conditions like towing or winter driving can drop the mileage significantly. 
This video discusses the fuel economy of the Chevy Silverado 2500's 6.6 gas engine: 57sGetty's GarageYouTube · Oct 27, 2025
Factors affecting MPG

• Model Year: The 2024 and 2025 models with the 10-speed transmission may have slightly better fuel economy in some situations than older models with a 6-speed transmission. 
• Trim Level: Base trims like Work Truck, Custom, and LT tend to have better MPG ratings, while higher-end trims like LTZ and High Country are less fuel-efficient. 
• Driving Conditions:
  • City vs. Highway: Expect lower mileage in city driving compared to highway driving. 
  • Towing and Hauling: Towing a trailer, especially a heavy one, will significantly decrease fuel efficiency. 
  • Driving Habits: Aggressive driving, such as speeding or hard acceleration, will negatively impact MPG. 
• Other factors: Vehicle weight, tire pressure, aerodynamics, and engine maintenance all play a role in overall fuel economy. 

You can watch this video to see a highway MPG test of the 6.6 gas engine: 58sAdventure RocksYouTube · Jan 31, 2024

What's better, 6.6 gas or diesel?

The main differences are that the 6.6L gas engine has lower initial cost, higher payload, and is better for lighter use, while the 6.6L diesel engine is built for heavy-duty towing with significantly more torque, better fuel efficiency when towing, and higher resale value. The diesel engine requires more costly maintenance and potentially more expensive fuel, and it may have lower fuel economy if not used for heavy towing or long trips. 
This video compares the gas and diesel engines in terms of horsepower and torque: 1mOutdoors With The MorgansYouTube · Apr 10, 2024
6.6L Gas

• Performance: Stronger horsepower for everyday acceleration, but less torque for pulling heavy loads. 
• Cost: Lower initial purchase price. 
• Maintenance: Simpler and cheaper to maintain, especially for repairs like a fuel pump. 
• Payload: Typically has a higher maximum payload capacity because the engine is lighter. 
• Best for: Lighter-duty use, less frequent towing, and drivers who prioritize lower upfront costs and simpler maintenance. 

6.6L Diesel

• Performance: Substantially more torque, which is ideal for heavy-duty towing and hauling. 
• Cost: Higher initial purchase price, more expensive diesel fuel, and higher maintenance costs, particularly after the warranty expires. 
• Maintenance: More complex and expensive to maintain and repair. 
• Fuel Economy: Better fuel efficiency when towing heavy loads or for long-distance highway driving. 
• Best for: Heavy towing, long trips, commercial use, and drivers who prioritize low-end pulling power and long-term durability. 

How many miles per gallon does a Chevy 2500 HD diesel get?

Diesel engines typically achieve 20 to 25 miles per gallon in the Silverado 2500, providing 30% to 35% better fuel efficiency than the gas variant. This makes diesel ideal for drivers looking to maximize mileage and performance, especially under demanding conditions.