What is the Fuel Mileage for 6.6 Duramax?

Wondering what the fuel mileage for a 6.6 Duramax is? We are going to be exploring that in this article so stick around. With LB7 being the very first Duramax of its kind, it is important to note that more reliable, fuel-efficient Diesel engines came after that.

The only difference this time is that most of the kinks in the first Duramax were now regulated and improved. The 6.6 Duramax came forth from a partnership of two very recognized and important car manufacturers, General Motors and Isuzu.

General Motors had been seeking to manufacture a much smaller, compact but impactful type of car which saves fuel while at it. General Motors had been constantly trying to restructure by changing its line of business from heavier cars, to the mentioned.

At the same time, Isuzu had been manufacturing the exact type of cars General Motors had been longing to manufacture as well. General Motors did not waste time as it quickly moved in on the opportunity to form a partnership with Isuzu.

What Gas mileage does a 6.6 Duramax get?

As Chevrolet pickups are still very hot-selling on the market, it’s important to take into consideration that most medium-sized pickup truck owners tend to often opt and go for the 6.6 Duramax Diesel engine.

This has been the case from the year 2001 to the present and this alone just says a lot about the fuel efficiency of the engine. We now want to dive into the details of the exact gas mileage the 6.6 Duramax has.

Related Post:  6.6 Duramax Oil Capacity: Amount of Quartz Required

Firstly, it should be noted that the gas mileage (mpg) is highly dependent on a few factors such as overall maintenance of the motor, how much cargo you’re carrying, how gentle or aggressive you are with it, and how much load you’re towing.

As mentioned by many first-Hand 6.6 Duramax users, using 3 specific vehicles that get fitted with the 6.6 Duramax are, GMC Sierra 2500HD, Chevrolet Silverado 3500HD, GMC Sierra 3500HD, and the Chevrolet Silverado 2500HD.

The latter has an MPG (average) that ranges from 13.1 to 15.5, the one before it has 10.9 to 15.2, followed by 11.6 to 14.1, and finally, the GMC Sierra 2500HD has an average MPG of 13.5 to 15.3.

What year does Duramax get the best MPG?

Naturally, diesel trucks have always had a very strong gas mileage, in comparison to their gas engine counterparts as they have a stronger, more defined torque than the gas engines that have the same exact size as them. Which year then gets the best MPG for Duramax.

This is very tricky as the Duramax lineup has proved reliable and efficient over the years. However, the best MPG goes to the 2002 Duramax as it had an MPG of at least 15.

This is followed by the years 2004 and 2006 both having a 14.3MPG and 2008 with a 14.5 MPG. It should also be pointed out that the 2021 GMC Sierra which uses 6.6 has a 17 to 19 MPG, the only drawback is that it hasn’t been tested for within-town mileage.

How do you get 30 MPG on a Duramax?

A lot of modifications need to be done to be able to make the vehicle much more fuel-efficient. These modifications involve replacing older parts with newer effective ones, buying a new engine completely, and modifying the exhaust system and cooling system.

Related Post:  L5P Duramax Problems [How Long will it Last?]

Modifying the radiator, suspension system, drive shaft, transmission, and external vehicle components and using the right, designated fuel. All these factors have an overall contribution to affecting the MPG of the truck and so tackling them head-on will help the truck drivers get to use the car for longer at a more economic-friendly price as gas prices across the globe have actually increased.


As General Motors is recognized as having the most reliable and durable truck vehicles on the planet earth, it makes a huge difference to know that they actually use the Duramax engines and that includes the 6.6 Diesel engine as well!

Earlier Duramax models had huge challenges with emissions systems and injection pumps and now 6.6 is considered to be the best post/emissions phase Duramax Diesel engine. It also has its drawbacks but they are undoubtedly outweighed by its strengths which include 910 pound-feet torque and 455 horsepower.

In conclusion, this makes the 6.6 Duramax a very good engine as it is very reliable and durable as proven through the course of the years.

Leave a Comment