Used Peterbilt 579 Ultraloft: Specs, MPG, Sleeper Size and Owner Operator Benefits
The Peterbilt 579 Ultraloft: A Long-Haul Favorite
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The Peterbilt 579 Ultraloft is one of the most popular sleeper trucks on the road today. Drivers like it because it is comfortable, fuel efficient, and built for long haul work.
Owner operators and fleets both choose the 579 Ultraloft because it gives drivers more living space while helping trucking companies like yours control operating costs.
At Pedigree Truck and Trailer Sales, these used Peterbilts come with even more value like free extended warranties and specs proven to turn a profit.
Ready to buy? Take a look at The Best Used Peterbilt Ultralofts on the Market.
Why the Peterbilt 579 Ultraloft Stands Out
The Peterbilt 579 Ultraloft was engineered for long haul trucking. Drivers often spend weeks at a time living in their truck, so comfort, visibility, and ease of operation matter.
The Ultraloft offers:
• One of the largest sleeper cabs available in a production truck
• Excellent forward visibility from the driver seat
• Modern driver safety and monitoring technology
• Simple, ergonomic controls that reduce driver fatigue
Many drivers say the 579 Ultraloft feels more like a small room than a traditional truck cab. That extra space makes long trips easier and reduces stress on the road.
We caught up with Pedigree customers Emory and Sheila Mains from Wheel Livin to hear their experience with the truck.
“The Peterbilt brand has decades of reliability and functionality. It has the largest bunk in a production sleeper which works best for my wife and I since I am a solo driver. She handles all the paperwork so the pull-out shelf on the passenger side dash is a must-have.
We started out at Prime Inc with a 2025 Peterbilt 579 lease and loved the truck so much that we decided to buy our own through Pedigree. We purchased a 2023 Peterbilt 579 and playfully named him Re-Pete. We love our Peterbilt and would not drive any other brand.”
Built for Long Haul Comfort
One of the biggest reasons drivers choose the Peterbilt 579 Ultraloft is the sleeper design.
The Ultraloft includes an 80 inch sleeper with a high roof, giving drivers enough room to stand, move around, and organize their living space.
Inside the sleeper you will find:
• Upper and lower bunk sleeping options
• Storage cabinets and shelves for gear
• Space for appliances such as refrigerators and microwaves
• Improved insulation for a quieter cab environment
For drivers spending weeks on the road, the additional living space makes a major difference in comfort and quality of life.
Peterbilt 579 Ultraloft MPG: What Drivers Actually Get
The Peterbilt 579 Ultraloft is one of the most fuel efficient sleeper trucks on the road today, and at Pedigree, our trucks are specifically spec’d to maximize fuel savings and profit.
Fuel is one of the largest operating costs in trucking, so miles per gallon directly impacts your bottom line. Many drivers running our trucks report 8.5 to 9+ MPG in real world long haul operations when driven efficiently.
Every 579 Ultraloft we sell is built from the same proven Prime Inc. fleet spec. These trucks are engineered to run efficiently across thousands of miles, not just perform on paper.
Our trucks are equipped with the PACCAR MX-13 engine, delivering consistent power while staying in an efficient operating range. This is paired with the PACCAR TX-12 automated transmission, which is tuned to keep the engine in its most fuel efficient RPM range.
Aerodynamic fairings and smooth body panels reduce wind resistance, allowing air to move cleanly around the truck and trailer. This directly improves fuel economy at highway speeds.
The result is a truck that is designed to control fuel costs, reduce driver fatigue, and produce consistent, predictable performance week after week.
These trucks are not just spec’d to run. They are spec’d to save fuel and make money.
PACCAR MX-13 Engine Reliability
Stories online about MX-13 engine failures often come from trucks that were poorly maintained. Many of the major problems people discuss share the same cause: deferred maintenance and excessive idling.
The PACCAR MX-13 engine is not an engine that tolerates neglect.
Prime Inc. fleet trucks are professionally maintained on strict preventive maintenance schedules. Every service was completed on schedule and documented by certified technicians.
PACCAR also stands behind the engine. The MX-13 includes 5 years or 600,000 miles of warranty coverage for both the engine and emissions system.
It is also important to understand where many online complaints originate.
Most negative feedback relates to the 2013 to 2017 EPA13 generation of the MX-13 engine. That generation had known aftertreatment issues when trucks were poorly maintained.
The MX-13 engines in these 2023 trucks are a significantly updated platform with improved aftertreatment calibration, fuel system revisions, and cleaner emissions technology.
You are not buying an internet opinion.
You are buying a truck with documented service history.
Power That Moves Freight
The PACCAR MX-13 produces 1,650 lb-ft of torque at only 900 RPM, which means the engine begins pulling hard before many engines even reach their power band. That low-RPM torque is what helps drivers maintain speed while pulling heavy loads without constantly burning extra fuel.
The PACCAR TX-12 automated transmission is tuned to keep the engine operating in that efficient torque range. Combined with the 2.64 gear ratio, this setup is designed to maximize fuel economy while still delivering strong pulling power.
This drivetrain configuration is not random.
These trucks were originally spec’d for Prime Inc., one of the most fuel efficient fleets in North America. Their engineers tune thousands of trucks to balance power, fuel efficiency, and long-haul durability across millions of miles of real-world operation.
Because of that optimization, the trucks we sell at Pedigree are spec’d exactly the same way.
Every one of our 2023 Peterbilt 579 Ultraloft trucks includes:
• PACCAR MX-13 engine with 455 horsepower
• 1,650 lb-ft torque at 900 RPM
• PACCAR TX-12 automated transmission
• 2.64 rear gear ratio for fuel economy
• two 100 gallon fuel tanks for extended range
This setup allows drivers to pull freight efficiently while maintaining strong fuel economy.
Higher horsepower engines can consume more fuel in terrain where the extra power is rarely needed. A properly balanced drivetrain like this keeps the engine operating in its most efficient range.
More torque combined with better fuel economy means lower cost per mile and more profit at the end of the week.
Why Drivers Buy Their Peterbilt 579 from Pedigree
Drivers across the country choose Pedigree Truck & Trailer Sales because these trucks come directly from the Prime Inc. fleet.
Prime operates one of the most fuel efficient trucking fleets in North America. Their trucks are spec’d for long haul efficiency and professionally maintained from the day they enter service.
When these trucks arrive at Pedigree, they include complete maintenance records showing every service performed throughout the truck’s life.
That level of transparency is rare in the used truck market.
Drivers know exactly how the truck was maintained and how it performed in fleet service.
What Extras Come With Every Pedigree Peterbilt
Most used truck dealers sell trucks exactly as they are.
At Pedigree Truck & Trailer Sales, every Peterbilt includes additional equipment already installed at no extra charge.
Every Pedigree Peterbilt includes:
• 10 new virgin dual tires installed at all positions
• ThermoKing APU
• bunk heater to reduce idling
• deer guard
• power inverter
• new dorm style refrigerator
• new mattresses on both bunks
• full fluid service
• DOT inspection
• professional detailing
• alignment
• complete lifetime service records from Prime Inc.
If you added these items at retail pricing, the value would typically fall between $10,000 and $15,000 in additional equipment.
Very few dealerships in the country bundle this level of equipment with their trucks.
Specs and Highlights of the 579 Ultraloft
Here are the features that make the Peterbilt 579 Ultraloft stand out in the used truck market.
• Spacious 80 inch sleeper cab with tall ceilings and double bunk options
• PACCAR MX-13 engine designed for durability and fuel efficiency
• Automated transmissions that are easier to drive
• Advanced aerodynamic design for improved fuel economy
• Driver focused interior with ergonomic controls and modern technology
Finding a Used Peterbilt 579 Ultraloft
Buying a used Peterbilt 579 Ultraloft can save drivers tens of thousands of dollars compared to purchasing a new truck.
These trucks are engineered to run for years when properly maintained.
When shopping for a used truck, drivers should look for:
• documented maintenance history
• reliable engine and transmission components
• comfortable sleeper configurations
• fuel efficient specifications
This is exactly why many drivers choose trucks from Pedigree Truck & Trailer Sales.
Every Peterbilt at Pedigree comes from the Prime Inc. fleet, one of the most professionally maintained trucking fleets in North America. Each truck includes complete lifetime service records, allowing buyers to see exactly how the truck was maintained throughout its life.
Pedigree trucks are also spec’d for fuel efficiency, long haul reliability, and driver comfort, because they were originally designed to operate in a fleet running millions of miles every year.
When you purchase a truck from Pedigree, you are not guessing how the truck was maintained. You are buying a truck with documented service history and proven fleet performance.
That level of transparency is one of the reasons drivers across the country choose Pedigree when purchasing a used Peterbilt 579 Ultraloft.
Final Thoughts
The Peterbilt 579 Ultraloft remains one of the most respected sleeper trucks in the industry.
Its combination of driver comfort, strong fuel economy, and proven long haul durability has made it a favorite among fleets and owner operators alike.
With its spacious sleeper, aerodynamic design, and efficient powertrain, the Ultraloft is built for drivers who spend serious time on the road.
If you are considering upgrading your truck, explore the available inventory in The Best Used Peterbilt Ultralofts on the Market to see current options.