How many miles per gallon does a 2008 Duramax 3500 get?

In general, a 2008 Duramax 3500 delivers about 15–18 miles per gallon combined, with highway mileage typically higher (high teens to low twenties) and city mileage usually in the low to mid-teens. Actual numbers depend on configuration and usage.

What affects MPG on the 2008 Duramax 3500?

Various factors influence the fuel economy of a 2008 Duramax 3500. The following elements commonly have the biggest impact on mpg in daily use:

• Drivetrain configuration: 2WD vs 4WD; axle ratio and transmission type


• Towing and payload: heavier loads drastically reduce efficiency


• Cab and bed configuration: crew cab, long bed, and overall vehicle weight


• Tire size and condition: larger or low-profile tires increase rolling resistance


• Engine maintenance: air filter, fuel injectors, exhaust aftertreatment, and overall tune


• Driving conditions and habits: city stop-and-go vs steady highway cruising; speed and idle time


• Elevation and weather: cold starts and altitude can lower efficiency

Understanding these factors helps set realistic expectations for fuel economy in the 2008 Duramax 3500.

Estimated MPG ranges for the 2008 Duramax 3500

Note: MPG figures vary by configuration, payload, and driving style. The ranges below reflect typical real-world performance and commonly cited estimates for diesel-heavy HD pickups from that era.

• City driving: approximately 12–15 miles per gallon


• Highway driving: approximately 17–22 miles per gallon


• Combined driving: approximately 15–18 miles per gallon

Real-world numbers can deviate by about 2–5 mpg depending on payload, towing, tire choice, and maintenance.

Practical tips to optimize MPG on the 2008 Duramax 3500

While the fuel economy figures above depend on configuration and use, these practices can help you maximize efficiency where possible.

1. Keep tires properly inflated to the recommended pressure and ensure alignment is good.


2. Perform regular maintenance: change filters, use the correct oil grade, and maintain the exhaust and emission systems.


3. Plan efficient routes, combine trips, and minimize idling when possible.


4. Reduce drag and weight: remove unnecessary racks or accessories and avoid carrying excess payload.


5. Use cruise control on highways and maintain moderate speeds for better aerodynamics.

Adopting these practices can help the truck reach the higher end of its typical range, particularly on highway driving or lighter loads.

Summary

The 2008 Duramax 3500 is a heavy-duty diesel capable of roughly 12–15 mpg in city conditions, about 17–22 mpg on the highway, and around 15–18 mpg in mixed driving. Real-world results depend heavily on drivetrain, payload, towing, tire choice, maintenance, and driving habits. For those using the truck for frequent towing or hauling heavy loads, mpg will be toward the lower end of the range, while lighter use and steady highway cruising can push numbers up toward the upper end.

How many miles per gallon does a GMC 3500HD diesel get?

A GMC 3500 diesel's real-world fuel economy is typically between 14–18 mpg highway and 10–14 mpg in the city, but can vary significantly based on driving conditions. For example, highway speeds over 75 mph often result in lower MPG, while towing heavy loads can bring mileage down to 8-11 mpg or lower, and city driving averages 11-16 mpg. 
You can watch this video to see a real-world MPG test of a GMC Sierra 3500: 59sJB ReviewsYouTube · Nov 13, 2022
General fuel economy

• Highway: Expect around 14–18 mpg when driving unloaded on the highway. Some drivers report higher figures, up to 20 mpg, with sensible gearing at lower speeds. 
• City/Mixed: Real-world city or mixed driving typically results in 11–14 mpg. 
• Towing: Fuel economy drops significantly when towing. Numbers can range from 8–11 mpg or lower depending on the weight of the trailer and driving conditions. 

Factors that influence MPG

• Driving habits: Aggressive acceleration and hard braking will decrease fuel economy. 
• Towing: The heavier the load, the lower the MPG will be. 
• Tire pressure: Keeping tires properly inflated can improve efficiency. 
• Maintenance: Regular maintenance, including oil changes and air filter replacements, helps keep the engine running efficiently. 
• Speed: Driving at higher speeds, especially over 75 mph, can decrease fuel economy. 

How to maximize fuel economy

• Drive smoothly, avoiding rapid acceleration and braking.
• Use cruise control on the highway to maintain a consistent speed.
• Ensure tires are properly inflated.
• Reduce unnecessary weight and drag on the vehicle.
• Keep up with regular engine maintenance. 

What is the gas mileage on a 2008 Chevy 3500?

This engine also uses Chevy's active fuel management system to shut down four cylinders under moderate loads to save fuel. The Environmental Protection Agency rates the mileage at 14 city and 19 highway.

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 2008 GMC 6.6 diesel get?

The standard engine is a 353-hp, 6.0-liter V8, and a 365-hp, 6.6-liter turbodiesel that delivers 660 foot-pounds of torque is also available. It can haul up to 2,200 pounds of payload and tow a heavy trailer, and it returned 13 mpg overall in our tests.