X15 engine image

X15 Efficiency Series (2020)

Power 400 - 500 hp
298 - 373 kW
Torque 1450 - 1850 lb-ft
1966 - 2508 N•m
Certification EPA 2017

Efficiency Is More Than Fuel Economy.

The X15 Efficiency Series has the best fuel economy of any engine in its class, bar none. But there’s more to efficiency than miles per gallon. It’s having the best uptime in the industry, with the longest maintenance intervals so you can rack up more revenue miles every year. It’s having over-the-air connectivity so you don’t have to take time to visit a dealer for calibration updates. It’s real-time diagnostics that accelerate service accuracy and speed. It’s having the biggest, most capable parts and service network in the industry, so you can get rapid assistance no matter where your loads take you.


Heavy-Duty Truck Truck Equipment Manufacturers and Body Builders


The X15 is an efficient use of your money, with the best resale value of any engine in the industry. It all adds up to Total Cost of Ownership that puts your fleet miles ahead of the competition.

Lower RPM. Bigger Savings.

The 2020 X15 Efficiency Series takes advantage of refinements to its big-bore design and integration with transmissions to deliver better fuel economy with reduced Greenhouse Gas (GHG) emissions. Increased downspeeding means your drivers get all the performance they are used to at lower RPM. Not only does this reduce fuel consumption and emissions but engines that run at consistently lower speeds last longer with less wear and tear.

New EX Ratings. Up to 5% Fuel Economy Improvement.

Cummins new EX ratings feature the Endurant™ transmission from the Eaton Cummins joint-venture. As part of the Cummins integrated power portfolio, the EX ratings leverage technological synergies to deliver high fuel economy and smooth operation with extended service intervals. Bundled hardware and software makes spec’ing easier and more time-efficient. The value that Cummins is bringing to the trucking industry goes well beyond engine hardware. Rookies drive like pros with the fuel saving technologies offered on the X15 Efficiency Series.

The EX ratings are specifically designed for long-haul, cost-sensitive fleets. Advanced features make it easier for novices and experienced drivers alike to achieve not only the best fuel economy, but experience improved drivability and performance for better trip time and overall operational efficiency. Features that are exclusive to the X15 EX ratings include: Predictive Shifting, On-Ramp Boost, Predictive Braking and Dynamic Power. EX ratings require use of GPS data as well and pairing the X15 Efficiency Series with the Endurant transmission.

The Best Gets Even Better.

The X15 ratings for 2020 offer upgraded turbocharger aerodynamics and a high performance EGR cooler for overall air handling improvements for greater efficiency throughout the system. And, with changes like reduced water pump speed, there’s an overall reduction in parasitic losses throughout the system.

Uptime. All The Time.

When you purchase a piece of Cummins-powered equipment, you’re getting more than just a powerful, reliable and durable engine. You’re getting advanced technology and 24/7/365 coverage from Cummins Care, the most extensive and competent parts and service network (over 3,500 locations) in North America. X15 engines are equipped with our proven Connected Diagnostics system for rapid analysis if a fault is triggered. Connected Calibrations,™ our Over-the-Air (OTA) engine customization technology, lets you upgrade your engine calibration on the job site. There’s no need to visit a dealer to get the latest configuration. Everything we do is designed to reduce downtime and increase productivity – because that’s the fastest route to greater profits.


Advertised Horsepower 400-500 hp
298-373 kW
Peak Torque 1450-1850 lb-ft
1966-2508 Nm
Governed Speed 1700 RPM
Clutch Engagement Torque 1000 lb-ft
1356 Nm
Number of Cylinders 6
System Weight 3152 lb
1430 Kg
Engine (Dry) 2961 lb
1343 Kg
Aftertreatment System 191 lb
87 Kg
Rating Horsepower Peak Torque
400EX 400 1650 lb-ft
400EX 400 1750 lb-ft
400EX 400 1850 lb-ft
450EX 450 1750 lb-ft
450EX 450 1850 lb-ft
500EX 500 1850 lb-ft
400ST 400 1450/1650 lb-ft
400ST 400 1550/1750 lb-ft
400ST 400 1650/1850 lb-ft
450ST 450 1450/1650 lb-ft
450ST 450 1550/1750 lb-ft
450ST 450 1650/1850 lb-ft
500ST 500 1650/1850 lb-ft
450 450 1650 lb-ft
450 450 1750 lb-ft
450 450 1850 lb-ft
500 500 1650 lb-ft
500 500 1850 lb-ft
  • VGT Turbocharger – Highly reliable and precise design for rapid acceleration
  • XPI Fuel System – High pressure enables multiple injection events per cycle for industry-leading fuel economy and quieter operation 
  • Single-Module™ Aftertreatment System – A compact and lightweight system that offers increased ash capacity and extended maintenance intervals 
  • Fleetguard Fuel And Lube Filters – Superior holding capacity provides better protection and enables longer service intervals 
  • High-Capacity Electronic Control Module – This allows full integration of data inputs from all subsystems, optimizing performance
  • Cummins Engine Brake – With up to 600 braking horsepower, it’s the most powerful in the industry. Stronger braking capacity reduces wear on service brakes and replacement costs
<5.0 – 5.9 MPG
6.0 – 6.9 MPG
>7.0 MPG
40,000 Km
40,000 Mi
64,000 Km
50,000 Mi
80,000 Km
75,000 Mi
120,000 Km
48,000 Km
45,000 Mi
72,000 Km
55,000 Mi
89,000 Km
80,000 Mi*
130,000 Km
X15 OIL DRAIN WITH CUMMINS OILGUARD extensions available extensions available extensions available 100,000 Mi*
112,000 Km
FUEL FILTER2 25,000 Mi
40,000 Km
40,000 Mi
64,000 Km
50,000 Mi
80,000 Km
75,000 Mi**
120,000 Km
400,000-640,000 Km
  400,000-600,000 Mi
640,000-960,000 Km
600,000- 800,000 Mi
960,000-1,300,000 Km
DEF FILTER 250,000 Mi
400,000 Km
  280,000 Mi
448,000 Km
300,000 Mi
480,000 Km
800,000 Km
  500,000 Mi
800,000 Km
500,000 Mi
800,000 Km

* Cummins recommends Valvoline Premium Blue (PB 8600ES)
** Extending fuel filter interval from 60,000 miles to 75,000 requires use of extended filter available through Cummins service network.

1 - Up to 80,000-mile oil drain interval with participation in Cummins OilGuard oil analysis program.
2 - For Premium Blue users, the fuel filter interval matches the ODI.
3 - Maintenance lamp will illuminate when DPF cleaning.

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