What Affects Gas Mileage for a Truck?

If your fleet trucks are not getting the most mileage out of their fuel, the wasted money adds up over the course of their many trips and could prove costly.

It’s important for truck drivers and fleet managers to ensure they consider fuel mileage before purchasing a specific truck for their fleet. One of the most basic questions centers around the average gas mileage for a truck. Finding an answer, however, is hardly as simple as it sounds.

What is a Gross Vehicle Weight Rating(GVWR) How does GVWR affect gas mileage?

The Gross Vehicle Weight Rating is a number that lets you know how much your vehicle is allowed to weigh. Assuming you know the empty weight of the vehicle (that’s the weight of the vehicle with nothing else in it), the GVWR indicates how much extra weight you can add while still being able to safely operate the vehicle. That could be passengers or cargo.

“If it’s a 10,000-pound truck (GVWR) and weighs in at 7,800 pounds, you have 2,200 pounds of usable payload, (which is) what you can put on that truck,” explained Michael Olden, a commercial truck manager at truck dealership Lee-Smith, Inc. with nearly 30 years of automotive & truck experience.

The ratings are divided into eight classes to better organize the type of payload each vehicle can withstand. The classes are as follows:

  • Class 1: 6,000 lbs or less
  • Class 2: 6,000 to 10,000 lbs
  • Class 3: 10,001 to 14,000 lbs
  • Class 4: 14,001 to 16,000 lbs
  • Class 5: 16,001 to 19,500 lbs
  • Class 6: 19,501 to 26,000 lbs
  • Class 7: 26,001 to 33,000 lbs
  • Class 8: 33,001 and over

Adjustments in fuel usage and subsequent driving habits are necessary depending on where a vehicle falls within these classes. Truck drivers that find themselves in the heavier classes of trucks must be aware of the amount of the additional fuel they need to get to their destination.

What are other factors that can affect a truck’s gas mileage?

Vehicle size isn’t the only factor that can affect a truck’s gas mileage. According to Michael Olden, there are a handful of crucial elements that have to be considered by truck drivers and fleet managers alike.

Engine Horsepower

Horsepower is the amount of power the horse (or in this case, a car) needs to complete a certain type of work. The standard is calculated through the power needed to move 550 pounds one foot in one second or by the power one would need to move 33,000 pounds one foot in one minute.

If a truck has a high horsepower number, that means it can transport a bigger load of cargo faster than one with a low number. Of course, that might also mean the truck requires more fuel to keep it moving.

Engine Liter Size or Displacement

Engine liter size simply refers to the size of the engine determined by the amount of space that lies within an engine’s cylinders– the place where fuel combusts and power materializes.

The bigger the engine liter size, the more power a truck has. But, similar to horsepower, a bigger engine means that more gas is required to fill it up completely.

Engine Torque

A truck can come equipped with a massive engine and considerable amounts of horsepower, but if it doesn’t have the torque that’s needed to generate the energy those two components need to reach a certain speed, those factors only mean so much.

More torque makes it easier to shoulder the burden of a heavier payload and provides an additional boost a truck may need to make it up a specific hill.

Mike Olden explains how GVWR affects gas mileage.

Are you ready to learn more? Talk to a Fleet Advisor today.

Driving Terrain

Imagine two different roads leading to the same destination. One is a straight line. The other curves back and forth like an S. Which road do you think would require more gas? What about the truck that’s constantly driving through flat valleys compared to the ones that always find themselves driving up hills?

These are some of the environmental differences truck drivers must evaluate when analyzing their fuel efficiency. Two trips can be the same distance but require different amounts of fuel due to circumstances beyond control. 

What is the average gas mileage for a truck?

The truth is that there really isn’t a definitive average gas mileage for a truck because of the different variations and circumstances that accompany each one.

Some trucks have bigger engines and more horsepower. Certain trucks have the space to carry more cargo than others. And certain trucks require less fuel on account of their journey through the flatlands of the midwest compared to some of the hillier parts of the country that need more gas to conquer.

So when truck dealers sell a truck, they may not know what body the buyer will choose. “We don’t know if it’s gonna be a dump truck body, if it’s gonna be a refrigerated body, if it’s going to be a van, if it’s gonna be a food delivery truck,” Michael Olden said. “Food delivery trucks have different refrigeration systems. So you can’t tell somebody what the fuel efficiency is gonna be unless you know what body’s going to be on that truck.”

If you’d like to learn more about how GPS Trackit can help to improve safety, increase productivity and reduce costs for your business, speak with one of our knowledgeable Fleet Advisors at 866-320-5810 or get a quick Custom Quote.


  1. https://www.toyota.ca/toyota/en/connect/3887/what-is-horsepower
  2. https://www.whichcar.com.au/car-advice/what-is-engine-size-and-why-does-it-matter 
  3. https://www.kia.com/dm/discover-kia/ask/what-is-a-cylinder-in-a-car.html 
  4. https://www.sandicliffe.co.uk/blog/the-truth-about-torque-what-is-it-why-does-it-matter

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