All About Semi-Truck Fuel Efficiency

While semi-truck fuel efficiency has improved significantly over the past century, diesel is still one of the biggest expenses in the trucking industry. The average semi-truck gets around 6.5 miles per gallon (MPG) as opposed to the average car, which gets around 25 MPG. 


The difference in fuel economy between a passenger vehicle and a semi-truck is due to the considerable difference in weight. For semis, efficiency also depends on the make and model of the truck, how big of a load it is hauling, and if the truck is driving up or downhill.


Fuel efficiency is important for truck drivers because they often trek upwards of 100,000 miles every year. Although drivers don’t have a lot of control over the weight of their vehicle, there are some steps that can be taken to get the most mileage out of a full tank of fuel.


Follow these four tips for a more fuel-efficient vehicle:

1. Regulate Your Speed 

In any vehicle, maintaining a constant speed also maintains steady fuel usage. Try to stay in one gear for as long as possible as you follow the speed limit of the road. For every MPH increase above 55 MPH, the vehicle’s fuel efficiency reduces by 0.1 MPG.

2. Avoid Idling 

Another way to get the most out of your tank is to avoid idling whenever possible. Many drivers leave their vehicle running so they can run an errand, maintain its internal temperature during extreme weather, or avoid restarting it. However, it is a good rule of thumb to not leave your semi idling for longer than five minutes at a time. Each hour of idling your truck can burn a gallon of diesel and contribute to decreasing fuel efficiency. 

3. Take Advantage of Cruise Control 

Excessive acceleration and braking will negatively affect the fuel efficiency of your semi-truck. Taking advantage of cruise control will keep you driving at a steady and safe speed at all times. Just be sure you continue to pay close attention to the road. 


You can also try coasting when possible. Driving a heavy truck builds up a lot of momentum. Periodically using this built-up momentum rather than the gas pedal to propel you forward can add up and save you on fuel.

4. Check Tire Pressure 

In addition to making sure you choose the right tires for your vehicle, it will also help fuel efficiency to keep them in good condition. Check your tire pressure regularly to make sure they are not underinflated. If your tires are underinflated by 10 pounds per square inch (PSI), your fuel consumption increases by 1.5%. 

Additional Tips

A few more ways to maximize fuel efficiency in your semi-truck are:


  • Watch out for slippery roads.
  • Stay in top gear and shift as little as possible.
  • Don’t overfill your fuel tank.
  • Fix your roof-mounted air deflectors. 

Earn your CDL with Us

If you are interested in pursuing a truck driving career, take the first step by earning your commercial driver’s license (CDL). At Phoenix Truck Driving Institute, we can help you get on the road in as little as four weeks.

To learn more about how to earn your CDL through our training program, contact us today.

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