How To Get 30+ MPG With A Duramax
October 15, 2020

How to Get 30+ MPG with a Duramax

Written By: ProSource Diesel

Is it possible to increase the fuel economy of your Duramax truck using aftermarket Duramax parts? New diesel trucks are getting more expensive, so it makes sense that owners are trying to keep their older rigs on the road longer and get good gas mileage at the same time. It may be possible to upgrade some of your diesel truck parts for better performance and fuel economy.

Let’s take a look at how to get 30+ MPG with a Duramax.

General Tips for Better MPG

Before we get into upgrades and other methods, there are four tried and true tips that can coax extra gas mileage from your truck.

  1. Don’t let your truck idle for long periods of time if you can help it. Idling burns a lot of fuel and your gas mileage will take a hit.
  2. Don’t be heavy on the gas. Brisk acceleration burns more fuel than slow and conservative acceleration.
  3. Watch your tire pressure. Tire pressure is most important for city driving. You’ll lose roughly one percent of fuel efficiency per 10 PSI below the recommended amount.
  4. Service and maintain your Duramax truck regularly. Failing or worn Chevy Duramax parts can be culprits in reduced fuel economy.

Average MPG for Stock Duramax Trucks

The average MPG for a truck with a Duramax engine varies depending on the truck model as well as on which Duramax engine it has. For example, the 2020 Chevy Silverado 1500 with the 3.0-liter Duramax turbo-diesel gets an EPA-estimated 33 MPG on the highway and 23 MPG in the city. This is with the two-wheel-drive model. The four-wheel-drive of the same model gets a bit less on the highway at 29 MPG.

Of course, as you go further back into older models of diesel trucks and bigger Duramax engines, the fuel economy naturally goes down. The 2016 GMC Canyon gets a combined average of 24 MPG, while the much larger 2016 GMC Sierra 3500 HD gets about 12.6 MPG combined. Combined fuel economy is a weighted average of city and highway MPG values. It is calculated by weighting the city value by 55% and the highway value by 45%.

Find Your Truck’s Current MPG

Because mileage on any vehicle can vary depending on how it’s driven and its condition, you’ll want to find out what kind of MPG you’re getting currently before making attempts to increase it. Start by recording two fill-ups.

  • Fill your tank all the way
  • Reset your trip odometer or record the mileage on your master odometer
  • Drive for at least half a tank of gas
  • Fill your tank all the way up again
  • Record how much gas it took to refill
  • Record how many miles you drove based on your last and current odometer

Divide how many miles you drove by the amount it took to refill your tank. For example, if you drove 100 miles and it took 7.5 gallons to refill, then you’re getting about 13.3 MPG.

Options for Increasing MPG

What are your options for increasing your MPG? Some popular methods include:

Some of these options, like minimizing AC use, installing a bed cover, and removing the tailgate, give you very minimal MPG gains. On the other hand, tuning and upgrades can give you significant MPG gains. It might not be enough to get your truck up to 30 MPG, but if you’re only getting 13-14 MPG, you may be able to get closer to 20.

Tuning for Extra MPG

Diesel engines are designed to produce high low-end torque. At the same time, manufacturers need engines to trend towards reduced emissions. This conflict causes manufacturers to trade low-end torque for torque at increased RPM. If you can tune your truck to shift the torque back to the low-end, it enables you to get more power with less energy. That means significantly improved gas mileage. Tuning enthusiasts often claim they can get up to 7 MPG extra through this method.

Air Intake Upgrades

By giving your truck better airflow, you can improve both performance and gas mileage. Being proactive in replacing the air filter when it gets dirty can help, but you can also make a small modification to your factory airbox to let more air in. A triangular section on the lower part of the airbox can be removed by cutting through the plastic. Use a file to smooth the edges before reinstalling the box. This creates an extra spot for your filter to pull in fresh air.

New Fuel Filter

Similar to regularly changing out your air filter, it’s important to do the same to your fuel filter. A clean fuel filter is necessary for your Duramax engine to get its best performance and mileage. Your fuel filter should generally be changed between 12,000 and 15,000 miles.


If you’re trying to figure out how to get 30+ MPG with a Duramax, these tips could get you close. Gaining fuel economy on your Duramax truck can be done through proactive maintenance, driving habits, and modifications. Some modifications, like the airbox mod listed above, cost next to nothing and are simple to perform. Other modifications can get expensive quickly. If your primary reason for modding is fuel economy, make sure you run the numbers and see if the gains are worth the cost.

Rely on ProSource for a wide selection of 6.6 Duramax performance parts and aftermarket 6.6 Duramax parts to increase your gas mileage and keep your truck running great for a long time. ProSource Diesel is where repair shops shop for hard-to-find diesel truck parts and kits.

Duramax parts at ProSource Diesel

1 Comment

  1. Lacy Prodan on May 19, 2021 at 3:14 PM

    I love it when people get together and share views. Great website, keep it up!

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