How many miles per gallon does a 2002 Duramax diesel get?

Typical real-world fuel economy for a 2002 Duramax diesel pickup sits in the mid-teens overall, with highway efficiency often in the 18–22 mpg range and city driving around 12–15 mpg. Towing or carrying heavy loads can reduce mpg further.

This article examines the 2002 Duramax LB7-powered Chevrolet Silverado 2500HD and GMC Sierra 2500HD, explains why mpg varies, and provides owner-reported ranges and practical tips to estimate and improve fuel economy.

Context and drivetrain in the 2002 Duramax

The 2002 Duramax refers to the 6.6L V8 diesel engine (LB7) paired with the heavy-duty Allison automatic transmission, used in Chevrolet Silverado 2500HD and GMC Sierra 2500HD models of that era. Fuel economy depends on factors such as drivetrain (2WD vs 4WD), axle ratio, payload, and towing load, as well as driving conditions and maintenance.

Key factors that affect fuel economy on a 2002 Duramax diesel

• Drivetrain configuration, including two- or four-wheel drive and axle ratio


• Towing and payload weight


• Terrain, hills, and driving style (acceleration, gearing, idling)


• Maintenance and fuel quality (air filter, fuel system, injectors)


• Tire size and inflation pressure


• Aftermarket modifications (tuning, exhaust, intake restrictions)

In practice, these elements create a wide range of mpg outcomes, so real-world numbers vary considerably from the headline estimates.

Typical MPG ranges by driving scenario

Below are approximate ranges reported by owners under common usage. These should be treated as rough guides rather than precise EPA figures.

• City driving (stop-and-go, urban congestion): 12–15 mpg


• Mixed driving (city + highway): 14–18 mpg


• Highway cruising with light payload: 18–22 mpg


• Towing or heavy payload: 10–14 mpg

Actual results depend on the truck’s condition, configuration, and how it’s used. These ranges reflect typical experiences from owners of 2002 Duramax-powered pickups.

Tips to maximize fuel economy

To squeeze more miles per gallon from a 2002 Duramax, consider practical steps that cover driving behavior and maintenance.

Driving habits

Adopt smooth, steady acceleration, anticipate stops, and use cruise control where appropriate. Tow with appropriate gearing and avoid lugging the engine.

• Maintain steady speeds and minimize rapid acceleration


• Use the correct gear and avoid engine lugging


• Avoid prolonged idling and excessive high-speed driving


• Keep tires inflated to the manufacturer’s recommended pressure


• Remove unnecessary weight and reduce aerodynamic drag

These driving adjustments can yield noticeable gains, especially when combined with proper maintenance.

Maintenance and equipment

Maintenance and proper equipment can improve efficiency more than many expect.

• Replace the air filter regularly and keep the intake free of obstructions


• Use high-quality fuel and follow the recommended schedule for fuel filter changes


• Keep the exhaust and emission-control systems in good condition


• Ensure correct wheel alignment and tire rotation; fix drag-related issues


• Avoid aftermarket parts that reduce efficiency unless necessary

Regular service and attention to these items help maintain more consistent fuel economy.

Summary

For a 2002 Duramax diesel pickup, real-world fuel economy typically falls in the mid-teens overall, with highway mileage often higher than city driving. Expect roughly 12–15 mpg in urban use, 14–18 mpg in mixed conditions, and 18–22 mpg on long highway trips with light loads. Towing or carrying heavy payloads reduces efficiency, while disciplined driving and diligent maintenance can improve results.

How many miles per gallon does a LB7 Duramax get?

An LB7 Duramax engine, found in 2001-2004 GM trucks, typically gets about 17-19 MPG on the highway and 15-17 MPG in the city when stock. However, mileage can vary significantly based on driving conditions, modifications, and maintenance, with some drivers reporting much higher numbers with tuning or more moderate figures when towing or in heavy city traffic. 
This video shows an example of a real-world fuel mileage calculation for an LB7 Duramax: 49s2nd Momentum GarageYouTube · Jan 2, 2020
Typical mileage

• Highway: 17-19 MPG
• City: 15-17 MPG 

Factors that affect MPG

• Modifications: Tuners, aftermarket air intakes, and exhaust systems can improve or worsen fuel economy depending on the setup. 
• Towing: Towing heavy loads can significantly decrease mileage to 10-13 MPG. 
• Driving habits: Aggressive driving and higher speeds will reduce MPG, while maintaining a steady speed, especially around 55-60 mph, can improve it. 
• Truck condition: Engine health, maintenance, and modifications all play a role in the final MPG you achieve. 

You can watch this video to learn about ways to potentially improve MPG: 1mJW MontoyaYouTube · Dec 28, 2017
What to expect

• A stock LB7 will likely fall within the typical range. 
• Owners report a wide range of results, from as low as 13 MPG in some conditions to over 20 MPG on the highway for those with certain modifications and light-footed driving habits. 
• It's not uncommon to see variations between the truck's computer display and hand-calculated mileage. 

How many miles per gallon does a 2002 Chevy 2500 6.6 Duramax get?

This engine is mated to a 5-speed Allison automatic transmission. This engine/tranny is a good pairing and I have averaged around 17.5 MPG in day-to-day driving (when not towing or hauling heavy loads). This is drastically more efficient than a comparable HD truck of the same vintage with a gasoline V8.

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

What is the gas mileage on a 2002 Duramax LB7?

16 to 17 miles
16 to 17 miles or 25 to 27 kilometers per gallon.