Have it all with the X15 and X12 Euro VI Powertrain lineup.
With a focus of uptime, total cost of ownership and ease of operations, the Cummins heavy-duty truck engine platforms bring you the best 15-litre and 12-litre engines yet. Starting with the most reliable 15-litre ever produced, to offering EX ratings for enhanced driver performance, the X15 and X12 give you the confidence needed to improve your business without sacrificing anything.
X15 Euro VI Performance Series
The power of versatility.
The X15 Performance Series gives you the ultimate flexibility suitable for both manual and automated transmissions, vocational, heavy-haul and line-haul applications.
With ratings up to 625 hp and 2050 lb-ft of torque available at 1000 rpm, the Performance Series ratings are optimised for application flexibility.
X15 Euro VI Efficiency Series
The power to save.
If you want the power to save on your bottom line, then meet the new Cummins X15 Efficiency Series – with the advantage of reaching to 900 RPM and still improving over Euro V.
Power under weight-sensitive applications
X12 Euro VI
The best of all worlds.
Cummins is the undisputed global leader in high-performance diesel engines in on highway applications. For nearly two decades, the Cummins X Series platform has continually set new standards for power, productivity, low cost of operation and total value.
Learn about tomorrow - today
The 2027 X15
Introducing the 2027 X15 engine. The next step in the Cummins HELM™ 15-liter platform. Offering up to 605 hp and 2,050 lb-ft torque, this engine demonstrates our continued commitment to the evolution of internal combustion technology.
X10
Introducing the new Cummins X10, a next generation engine that brings a state-of-the-art platform to medium-duty, heavy-duty, vocational, and transit bus applications, launching in North America in 2026. This engine is uniquely positioned to replace both the L9 and X12.
Choosing the right heavy-duty truck engine
Cummins diesel engines are favorites in the North American heavy-duty truck market. Drivers, owner/operators, and fleet managers agree: Cummins engines are among the most powerful and reliable Class 8 truck engines on the road.
Heavy-duty truck engines by use case and primary benefit
| Use case | Primary benefit | Engine recommended |
|---|---|---|
| Long hauls | Efficiency | X15 Efficiency Series |
| Multi-purpose | Continual access to peak horsepower | X15 Productivity Series |
| Premium linehaul | More than 500 HP | X15 Performance Series |
| Weight-sensitive vocational or regional haul | Maximum payload | X10 Engine |
Heavy-duty truck fleet optimization tools
Make confident decisions faster with tools that simplify your journey
Pacific Haulage stands tall in the timber industry Pacific Haulage was established in Gisborne on the North Island’s east coast in 1985 to service a five-year NZ Forest Service contract. Three men – Graham Manson, Mike Treloar and Calvin Paddon who had worked together in the forestry industry in the 1970s as diesel mechanics – joined forces to establish the business with, as Treloar puts it,
Livestock transportation company moves millions of livestock each year Established 73 years ago, Frasers Livestock Transport may well be the oldest substantial livestock trucking business in Australia still under original ownership. Frasers today runs a fleet of 50 prime movers and 150 trailers operating as single, B-double, B-triple and roadtrain configurations. Home base is at Warwick in Q
When Warwick Wilshier bought a second-hand White Road Boss to go logging as an owner-driver in 1982, he wasn’t exactly planning to build the business that today is one of the stand-out names in New Zealand’s timber industry. Williams & Wilshier – Garry Williams is no longer a partner in the Rotorua-based business – operates 68 company log trucks while also having 20 fulltime owner-drivers.
Maarten Durent is a force to be reckoned with, as is the team he has built at New Zealand’s Southpac Trucks which won the prestigious Kenworth Dealer of the Year Award for the first time in 2017. Southpac sold over 230 Kenworths in 2017 and Durent is quick to reveal that, at the beginning of March, the company already had orders for more than 150 Kenworths for 2018. “In 2017 we actually sold
Fifty-four years ago, O’Neil Transport had its humble beginnings in Wallace in country Victoria. While interstate linehaul today accounts for around 50% of the company’s revenue versus 40% for regional transport and 10% for intermodal container transport, the O’Neils – Tony and wife Anne-Maree – still consider themselves very much a country carrier at heart. “We’ll always be a country or reg
Frequently asked questions
Heavy-duty truck engines are usually diesel or natural gas engines designed for Class 8 semi-trucks used in demanding commercial applications. These engines are built to deliver high horsepower to meet needs such as maximum payload capacity, long-haul efficiency, and continual access to peak power. These powerful engines are engineered for use cases ranging from weight-sensitive vocational and regional haul work to multi-purpose, long-distance commercial trucking.
The best heavy-duty truck engine is subjective and highly depends on your use case. We recommend the following based on the intended use:
- Long-haul efficiency: X15 Efficiency Series
- Multi-purpose with continual access to peak horsepower: X15 Productivity Series
- High horsepower (500+ HP): X15 Performance Series
- Maximum payload (weight-sensitive vocational or regional haul): X12 engine
To choose the right heavy-duty truck engine, please consider the needs for your use case:
- Long-haul efficiency: Choose the X15 Efficiency Series
- Multi-purpose with continual access to peak horsepower: Choose the X15 Productivity Series
- High horsepower needs (500+ HP / premium linehaul): Choose the X15 Performance Series
- Maximum payload (weight-sensitive vocational or regional haul): Choose the X12 engine
The following fuel types are available for heavy-duty truck engines:
- Diesel: A relatively cheap fuel that’s widely available and performs well with durable and reliable engines that provide all the torque needed for heavy-duty applications.
- Renewable Diesel (HVO): A fuel made from vegetable oils and animal fats. It can often be used as a drop-in replacement for diesel with no engine modification with net CO2 emissions typically 70% lower than diesel.
- Biodiesel: A renewable fuel most often blended with diesel. B20 blends balance cost and emissions and can generally be used with no engine modifications (always check with the manufacturer and truck manual before using).
- Natural Gas (CNG/LNG): A fuel that can be used in either compressed or liquefied form. Natural gas performs similarly to diesel with lower CO2 and reduced NOx and particulate emissions.
- Renewable Natural Gas (RNG): A fuel produced from biogas captured from organic waste. RNG can help fleets reach sub-zero greenhouse gas emission levels.
- Hydrogen: Cummins is developing hydrogen internal combustion engines, including a 15-liter and 6.7-liter version for heavy-duty commercial applications.
- Battery Electric: Battery electric trucks significantly reduce operating costs due to lower fuel and maintenance expenses. With zero tailpipe emissions, they contribute to cleaner air quality and the reduction of greenhouse gas emissions. Cummins offers battery electric solutions through Accelera™ by Cummins.
Cummins heavy-duty truck engines include the X15 Efficiency Series, X15 Productivity Series, X15 Performance Series, X12, X15N, the 2027 X15, and the new X10.
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Transportation has evolved since the beginning of time. What does the future of transportation hold?
Going further, faster
Today’s medium-duty fleets are faced with a growing demand to deliver high performance while lowering environmental impact.
Low and stable natural gas prices continue to draw attention from fleets and owner-operators looking to reduce operating costs while lowering emissions.
Maximizing fluid economy in a heavy-duty diesel powertrain begins long before a new truck delivers its first load.
MELBOURNE, AUSTRALIA - Cummins is advancing the conversation around heavy-duty transport performance at TruckShowX, building on the landmark debut of its fully integrated powertrain at the 2025 Brisbane Truck Show to demonstrate how the system delivers real-world results for fleets across Australia.
Summary Diesel powertrains and battery electric powertrains each offer distinct advantages depending on the application.
Summary Natural gas vehicles (NGVs) can offer commercial fleets significant fuel cost savings compared to diesel, with compressed natural gas (CNG) averaging $2.
