Next generation technology and big horsepower headlined the Cummins presentation when the 2025 Brisbane Truck Show opened on May 15.

The all-new X15D – the latest iteration of the Cummins 15-litre platform – is a high-performance, next generation diesel engine available exclusively with Euro 6 emissions compliance.

The engine is also known as the PX-15 in Paccar’s recently launched DAF XG+ cabover, which will be the first deployment of the engine in a 6x4 prime mover that has been developed exclusively for the Australian market.

“Cummins has taken internal combustion to the next level with the X15D,” says Sean McLean, Director and General Manager of On-Highway Business for Cummins South Pacific.

“It delivers the highest-ever outputs for a Cummins truck engine while setting new standards for fuel efficiency at ultra-low emissions levels.”

The X15D develops 660hp at 1800rpm with peak torque of 2360 lb-ft available across a wide band from 1400 down to 900 rpm. This supports Cummins’ advanced engine down-speeding strategy – designed to reduce cruise rpm for greater fuel economy while maintaining strong performance to satisfy both drivers and operators.

Another engineering feature is the engine’s weight advantage. With a dry weight 225kg lighter than the current X15, thanks to innovations like a sculpted iron block and composite oil pan, the X15D now delivers the highest power-to-weight density in the industry. For cabover applications, the reduced engine weight provides a notable benefit in lowering front axle tare.

The new engine platform also features the latest generation of Cummins’ Extreme Pressure Injection (XPI) fuel system and comes equipped with a standard wastegate turbocharger. Euro 6 compliance is achieved via an integrated single module aftertreatment system that houses both the diesel particulate filter (DPF) and the AdBlue SCR unit.

The X15D has already entered the Australian market under the PX-15 name in the DAF XG cabover, paired with ZF’s 16-speed automated TraXon transmission and Cummins-Meritor MT21-165 rear axles. The vehicle is rated for a gross combination mass (GCM) of 97 tonnes.

“The X15D will be available for other truck brands to meet Euro 6 requirements in the future,” says McLean, noting that even higher GCM applications will be supported following further local testing and validation.

“Initial field testing of the engine has focused on B-double type applications,” McLean says.

“Eighteen units rated at 660hp have been involved in the validation programme with customers, accumulating around six million kilometres.

“The programme has met our objectives and that was to gain feedback on fuel economy, performance and durability,” he says. “We’ve had great feedback, especially on driveability and torque.”

Further testing is ongoing with higher gross weight combinations to ensure the X15D continues to meet Cummins’ high standards of durability and performance. 

The X15D forms a core part of Cummins’ HELM platform - Higher Efficiency, Lower Emissions, Multiple Fuels - which features fuel-agnostic engine technology designed to operate on diesel, natural gas, or hydrogen. All variants are derived from a common base with high parts commonality, reducing complexity and streamlining maintenance.