How Many Miles Per Gallon Can a Semi Get? [Answer from Expert]

Are you a semi-truck owner? If yes, you must know how much MPG your truck gives on average.

To know this, first I will tell you what MPG means and how it is calculated.

MPG (miles per gallon) is a standard measurement of vehicle fuel efficiency. It indicates how many miles a vehicle can travel using one gallon of fuel.

The higher the MPG, the more fuel-efficient the vehicle is.

Calculation of the MPG of a vehicle

1. Fill Up the Gas Tank and set your trip odometer to zero, or note down the vehicle’s current odometer reading.
2. Drive your vehicle normally for a set distance.
3. Refill the Tank when it’s time to refuel, note how many gallons of fuel you used to refill the tank.
4. Note the Miles Driven or check your trip odometer since the last refill.
5. Use the MPG Formula

MPG=Miles Driven/Gallons of Fuel Used​

A typical semi-truck averages 6 to 8 miles per gallon (MPG). The average MPG can go higher or lower depending on the size and weight of a semi-truck. The MPG a semi gets can be crucial in managing operating costs.

How does engine size affect MPG?

1. Weight of the Load

A fully loaded semi-truck can carry loads weighing up to 80,000 pounds. It consumes more fuel compared to an empty or lightly loaded truck.

Heavier loads consume more fuel than lighter trucks.

2. Road and Driving Conditions

The type of terrain a truck drives on heavily influences MPG. Driving uphill requires more power and fuel than flat terrain.

Driving in bad weather conditions, such as heavy rain or snow, can reduce fuel efficiency as the truck needs to work harder to maintain traction. Cold weather makes engines less efficient, and winds can cause more drag, requiring more fuel to maintain speed.

3. Speed

The faster a truck travels, the more wind resistance it faces. Truck drivers maintain a steady speed of 55-65 miles per hour for optimal fuel efficiency. Exceeding this speed range can drastically reduce MPG.

4. Traffic and Idling

Sitting idle in traffic burns fuel without the truck moving. This greatly reduces overall fuel efficiency. It is good to turn off the engine in long traffic periods.

5. Maintenance

Regular maintenance is crucial to maintain optimal fuel efficiency such as

• oil changes
• filter replacements
• proper tire inflation

A well-maintained engine can contribute to better overall MPG. Tire pressure and engine must be kept properly to keep the truck running efficiently. Poor maintenance results in lower MPG.

6. Aerodynamics

Modern trucks with streamlined designs, including side skirts, tail fins, and cab modifications, reduce wind resistance, helping semi-trucks improve their MPG by reducing drag. Trucks with advanced aerodynamics can see an increase of 5-10% in fuel efficiency.

MPG Values for Popular Semi-Truck Models

Here’s a comparison of some popular semi-truck models and their average MPG:

Semi-Truck Model	Miles Per Gallon (MPG)
Freightliner Cascadia	8 – 9 MPG
Kenworth T680	7 – 9 MPG
Volvo VNL 760	7.5 – 8.5 MPG
Peterbilt 579	7 – 8.5 MPG
International LT Series	7 – 8 MPG
Mack Anthem	6 – 7.5 MPG

How to Improve Semi-Truck MPG

1. Optimizing Speed

Maintain a consistent speed of 55-65 mph to achieve optimal fuel efficiency. Avoid sudden speed changes and drive within this range to improve the overall MPG. Driving at a slow and consistent speed can

• Lower fuel consumption
• Maximize fuel efficiency
• Reduce wind resistance

2. Regular Maintenance

Ensuring the engine is maintained regularly and oil changes, air filter replacements, tire pressure checks, etc are done. It can significantly improve fuel efficiency.

Proper tire inflation can help reduce rolling resistance. Properly inflated tires do not consume more fuel than required. Under-inflated tires create more rolling resistance, and hence the truck uses more fuel.

3. Fuel-Efficient Tires

Low-rolling resistance tires are designed to reduce friction between the tire and the road. Using these tires can improve fuel economy.

4. Using Aerodynamic Modifications

Adding trailer skirts, cab extenders, and roof fairings can reduce wind resistance. As a result, trucks can cut through the air hastily. These modifications can improve fuel efficiency by 5-10%, making a noticeable difference over long-haul trips.

4. Idle Reduction Technologies

Semi-trucks often idle for extended periods, wasting fuel. Idle reduction technologies, such as auxiliary power units (APUs), allow the driver to power heating, cooling, and other electrical systems without running the engine. This reduces fuel consumption during rest stops or delays.

5. Adopting Predictive Cruise Control

Some modern semi-trucks come equipped with predictive cruise control, which uses GPS data to anticipate upcoming terrain and adjusts the truck’s speed accordingly. This technology helps maintain consistent fuel efficiency, especially on hilly or uneven terrain, improving overall MPG.

6. Improving Driver Training

Educating drivers on fuel-efficient driving techniques can lead to substantial fuel savings. Techniques such as smooth acceleration, minimizing idling, and avoiding unnecessary braking can make a significant impact on a truck’s fuel efficiency.