What is the mpg on a 2008 Duramax 3500?

A 2008 Duramax 3500’s fuel economy isn’t a single number; it varies by drivetrain, body style, and how the truck is used. In general, expect roughly 11–13 miles per gallon (mpg) in city driving and about 17–19 mpg on highways, with typical combined figures in the mid-teens. Real-world mileage can dip significantly when towing or carrying heavy payloads.

What affects the mpg of a 2008 Duramax 3500

The following factors have the biggest impact on mpg for this heavy-duty diesel pickup. Understanding them helps explain why numbers differ from one truck to another.

Drivetrain and drive configuration

Whether the truck is two-wheel drive (2WD) or four-wheel drive (4WD), and whether it uses a single rear wheel (SRW) or dual rear wheel (DRW) setup, influences fuel economy. 4WD and DRW versions tend to consume more fuel due to added weight and mechanical drag.

• 2WD SRW configurations generally deliver better highway efficiency than 4WD or DRW variants.


• 4WD versions usually show lower mpg in mixed driving due to increased drivetrain friction and weight.


• DRW (dually) tends to yield lower mpg than SRW, especially in stop-and-go city driving, though highway figures may not differ drastically on some trims.

In practice, the biggest mpg difference comes from whether the vehicle is used for heavy towing or payload versus everyday transport.

Payload, towing, and vehicle configuration

Carrying heavy loads or towing trailers markedly reduces mpg. The Duramax 6.6L diesel delivers strong towing capability, but that capability comes with a fuel-efficiency trade-off when under load.

• Light daily driving with no towing: higher mpg, closer to highway estimates.


• Moderate towing or payload: mpg drops noticeably, often into the low teens or high single digits if heavily loaded.


• Highway cruising with a light to moderate load tends to yield better mpg than city driving or steep grades with a trailer.

Engine performance and gearing also influence efficiency, particularly when towing long distances or traversing hilly terrain.

Typical mpg ranges for the 2008 Duramax 3500

EPA estimates for the 2008 Duramax 3500HD varied by drive type and body configuration. The following ranges reflect common setups for Silverado/Sierra heavy duties in that model year.

• 2WD (SRW, non-dually): City approximately 11–13 mpg; Highway approximately 17–19 mpg; Combined around 14–15 mpg.


• 4WD (SRW or CRW), regular to larger cabs: City approximately 11–12 mpg; Highway approximately 16–18 mpg; Combined around 13–14 mpg.


• 4WD with dual rear wheels (DRW): City approximately 11–12 mpg; Highway approximately 16–18 mpg; Combined around 13–14 mpg.

These figures are indicative ranges from that era and can vary by engine variant, transmission, axle ratio, and cab/bed choice. Real-world numbers often diverge from EPA estimates depending on driving style and conditions.

Real-world mileage and typical driving scenarios

Owners and drivers tend to report a broad spread in actual fuel economy depending on usage. The following notes capture common experiences with a 2008 Duramax 3500.

• Mixed daily driving (city and highway, no heavy towing): typically 12–16 mpg combined.


• Highway cruising with light loads and steady speeds: often 17–22 mpg observed by some drivers, though efficiency can vary with aerodynamics and tire size.


• Towing or hauling heavy loads (including towed payloads): frequently 8–12 mpg or lower, depending on trailer weight and terrain.

Actual fuel economy will vary widely based on load, grade, traffic, tire size, tire pressure, and maintenance condition. Regular maintenance and sensible driving can help you approach the higher end of these ranges.

Tips to maximize mpg on a 2008 Duramax 3500

Improving efficiency on a diesel-heavy pickup hinges on reducing drag, weight, and engine work where possible. Consider these practical steps.

1. Keep tires inflated to the recommended pressure to minimize rolling resistance.


2. Remove unnecessary weight and reduce payload when not towing.


3. Plan trips to minimize idling and combine errands into fewer trips.


4. Avoid excessive speeding; maintaining steady highway speeds around 60–70 mph can improve efficiency.


5. Ensure routine maintenance: clean air filters, clean fuel filtration, proper oil grade, and appropriate OEM-recommended fluids.


6. Use the lowest-to-tune gearing and axle ratio that still meets your towing needs to reduce engine work.


7. Minimize aerodynamic drag: remove roof racks or spoilers not needed for a given trip, especially at highway speeds.

By following these practices, you can often push an already efficiency-focused Duramax 3500 toward the upper end of typical mileage ranges for your specific configuration and usage scenarios.

Summary

The 2008 Duramax 3500’s mpg is not a single figure; it depends on drivetrain, cab/bed configuration, towing, and payload. Expect roughly 11–13 mpg in the city and 17–19 mpg on highways for many 2WD and 4WD setups, with combined figures typically in the mid-teens. Real-world mileage varies from about 12–16 mpg in mixed driving to 8–12 mpg when towing heavily. With mindful driving and regular maintenance, you can optimize fuel economy within these ranges.

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 Chevy 3500 get?

Get 15mpg with 12' NorthernLite Camper and 14mpg towing with the 8x10 cargo trailer with camper. 20mpg on highway with no load.

How to get better fuel mileage in a Duramax LMM?

The tow setting or street setting is typically the best option for maximizing MPG from the vehicle. I recommend switching to Diesel Kleen + Cetane booster additive to enhance fuel system cleaning and increase power by raising the cetane level. Additionally, upgrading the turbo compressor wheel can improve MPG.

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.