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

The typical fuel economy for a 2500HD with a 6.6-liter Duramax diesel is in the mid-teens to low-20s in highway driving, with real-world mileage strongly influenced by payload, towing, and drivetrain. On average, you’ll commonly see about 18 miles per gallon combined, with variations by year, configuration, and use case.

This article explains how MPG varies across generations of the Duramax 6.6L in the Silverado 2500HD, what EPA ratings look like for different setups, and what owners report in everyday driving. Because these trucks are designed for heavy payloads and towing, fuel economy is often lower when the truck is loaded or pulling a trailer.

EPA ratings and real-world mileage across generations

Below are typical ranges for common configurations across major Duramax generations used in the Silverado 2500HD. Exact numbers depend on model year, axle ratio, drivetrain (2WD vs. 4WD), and whether the truck is towing.

• Pre-2010 Duramax (early LB7 through LBZ/LLY era): typically around 15 mpg city and 20–21 mpg highway, with combined mileage commonly in the high-teens, especially for 4WD and higher gearing.


• 2011–2016 Duramax (LML era): generally about 15 mpg city and 20–21 mpg highway, with combined figures in the high‑teens; towing/showing improvements in highway efficiency but not dramatic changes in city economy.


• 2017–present Duramax (L5P era): often around 15–16 mpg city and 21–23 mpg highway, with combined mileage near 18–19 mpg in typical use; highway efficiency improves modestly, but payload and towing still dominate the profile.

In real-world conditions, these trucks frequently fall short of the EPA numbers when hauling, towing, or operating at higher speeds, and they may exceed the EPA estimates in light-duty, steady-speed highway cruising with moderate loads.

What affects fuel economy on a 2500HD with a 6.6L Duramax?

Fuel economy for these heavy-duty pickups is highly sensitive to several factors beyond engine displacement alone. The most impactful variables include payload, towing, driving speed, terrain, and mechanical condition.

• Payload and towing: Heavier loads dramatically reduce miles per gallon, often by a wide margin compared with unloaded highway cruising.


• Drivetrain: Two-wheel drive (2WD) versus four-wheel drive (4WD) changes rolling resistance and drivetrain losses, typically making 4WD slightly less fuel-efficient.


• Axle ratio and gearing: Lower numerical gear ratios (taller gears) generally improve highway MPG at steady speeds, while steeper gears assist torque for towing but hurt fuel economy.


• Terrain and speed: Flat, open highways at moderate speeds yield better MPG than hilly terrain or sustained high-speed driving.


• Maintenance and wear: Proper maintenance (air filters, diesel particulate filter condition, tire pressure, etc.) helps maintain optimal efficiency; worn injectors or a clogged DPF can reduce fuel economy.

Although the Duramax is built for durability and torque, the fuel economy is not its strongest selling point compared with light-duty diesels or smaller pickups. Buyers typically prioritize towing capacity and payload over maximum miles per gallon.

Tips to maximize MPG for a Silverado 2500HD with a 6.6L Duramax

Even small adjustments can yield noticeable gains when the truck is used for work or long highway trips. The following steps are practical ways to improve efficiency without compromising performance for heavy-duty use.

1. Keep tires inflated to the recommended pressure; underinflated tires increase rolling resistance and reduce efficiency.


2. Reduce unnecessary payload when possible; every extra pound adds to fuel consumption.


3. Maintain a steady speed on highways and use gradual acceleration to minimize turbo lag and fuel spikes.


4. Ensure the exhaust and intake systems are clean and free of obstructions; a clean DPF and properly functioning EGR system help efficiency.


5. Schedule regular maintenance, including air, fuel, and oil filters, and use the recommended diesel fuel grade for optimal combustion.

Ultimately, the best MPG comes from a combination of sensible use, careful maintenance, and an awareness of the truck’s towing and payload needs. Real-world numbers will always vary based on the specific build and usage pattern.

Summary

For a Chevrolet Silverado 2500HD with a 6.6L Duramax diesel, expect roughly 18 mpg combined under typical conditions, with about 15–16 mpg in city driving and 21–23 mpg on steady highway runs in modern configurations. Towing and heavy payloads will reduce efficiency, while proper maintenance and moderate speeds can help you approach the higher end of the range. Always check the EPA rating for your exact model year and configuration for the most precise 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 HD 6.6 get?

The Chevy Silverado 2500 HD with the 6.6L gas engine gets approximately 13-14 mpg in the city and 17-18 mpg on the highway, with a combined average around 15 mpg. Fuel efficiency can vary depending on the trim, driving habits, and load, with lower trims and more efficient driving yielding higher mileage.
 
City, highway, and combined MPG estimates

• City: 13–14 mpg
• Highway: 17–18 mpg
• Combined: ~15 mpg 

Factors that influence MPG

• Trim level: Higher trims like the LTZ and High Country are less fuel-efficient than lower trims. 
• Driving habits: Aggressive acceleration, towing, and carrying heavy loads will decrease fuel economy. 
• Tires and weight: The vehicle's weight and tire pressure can impact the MPG. 
• Aerodynamics: Aerodynamic drag plays a role in fuel efficiency. 

Real-world examples

• Some tests have shown a combined average of around 15.5 to 15.8 mpg. 
• Highway driving at steady speeds can result in 16 mpg or higher. 
• Towing can significantly reduce mileage, with one user reporting an average of 8.4 mpg while pulling a 7,000 lb camper. 

How many miles per gallon does a 2500hd Duramax get?

A 2500HD Duramax will typically get around 15-20 MPG, but this varies based on driving conditions, with highway driving yielding higher results (around 17-23 MPG) and city/towing driving lowering the average (around 12-15 MPG). Real-world fuel economy can also differ from the dashboard reading, so manual calculations are more accurate. 
Typical MPG ranges

• Highway: 17-23 MPG
• Mixed/City: 12-18 MPG
• Towing: Around 11 MPG, but this heavily depends on the trailer's weight 

Factors that influence fuel economy

• Driving conditions: Stop-and-go traffic, city driving, and short trips will result in lower MPG. 
• Towing: Towing a heavy load, such as a camper, will significantly decrease your fuel efficiency. 
• Idling: Excessive idling time can lower your average fuel economy. 
• Terrain: Driving on flat terrain will result in better fuel economy than driving on hilly or mountainous terrain. 
• Vehicle modifications: Aftermarket modifications like larger tires or lift kits can decrease MPG. 

1:01DURAMAX DIESEL, Real World Fuel MileageYouTubeOutdoors With The Morgans · 1y 0:472020 chevrolet Silverado 2500hd duramax average miles per gallonYouTubeMetal Works · 5y 1:00Here's the Real MPG on the 2024 Chevy Silverado HD DuramaxYouTubeTruck King · 2y (function(){
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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.