VIDEO CONTENT: The arrival of new ADL Enviro500 three-axle double decker buses to the Hong Kong franchised fleets during 2020 has taken the Cummins L Series engine population up to an in-service record high of 4,500 buses in the territory.

Built at the Cummins Darlington UK facility, the 8.9-litre engine has proven to be a robust performer in Hong Kong, operating for up to 20 hours daily on both city and rural routes, together with high-speed airport express services accumulating up to 200,000 km per year.

The latest Enviro500 three-axle double deck buses, specified for Hong Kong, feature the Euro VI certified L9 engine. Rated at 340 hp (254 kW) and with an impressive 1500 Nm peak torque at 1200 rpm, the Cummins L9 enables smooth and quiet operation when fully loaded with over 140 passengers.

The high-power density of the L9 provides generous levels of power-take-off for the heavy air-conditioning required in Hong Kong. A Cummins Variable Geometry Turbocharger (VGT) ensures rapid engine response for vehicle acceleration.

Hong Kong is home to the largest number of three-axle double deck buses in the world, with over 600 routes operated by the bus network, undertaking over 4.2 million passenger journeys every day.

Cummins powers almost 70 percent of the double deckers operated by the franchised bus fleets. The Cummins 8.9-litre engine can also be found powering Ankai sightseeing buses operating around the territory.

“Hong Kong presents an arduous bus duty-cycle with very high passenger loadings, a humid climate and steep gradients to climb, but Cummins L Series engine has proven to be more than equal to the task and we are delighted to reach a landmark population of 4,500 double deckers during 2020 in partnership with ADL,” said Ashley Watton, Cummins Director, Bus Business Europe.

“The L9 shares many heavy-duty design attributes such as the XPI fuel system with larger displacement Cummins engines, delivering premium performance but with the lower operating costs and fuel-efficiency of a compact, midrange engine,” added Mr Watton.

Equally impressive as the L9 engine performance is the service support provided by ADL and the Cummins Hong Kong support team, embedded at fleet depots and working together with the operators to maximize uptime.

Cummins also help the fleets to get the most out of their vehicles by providing technical support, delivering service training and introducing product improvements. 

The Cummins L9 engine is supplied with a fully integrated Selective Catalytic Reduction (SCR) and Diesel Particular Filter (DPF) exhaust aftertreatment system to meet the strict Euro VI emission standards required for new buses entering service in Hong Kong.

The combined SCR-DPF system is specifically designed for the 8.9-litre platform by Cummins and manufactured alongside the engine in Darlington, UK.

An insight into the operations of the Hong Kong bus network can be viewed in a Cummins video.                                    

The film pays tribute to the efficiency of the bus operators in keeping Hong Kong and its people connected, including dramatic drone footage of the buses in action, and a behind the scenes look at some of the major service depots across the city.

About Alexander Dennis Limited

Alexander Dennis Limited (ADL) is a global leader in the design and manufacture of double deck buses and is also the UK’s largest bus and coach manufacturer. ADL offers single and double deck vehicles under the brands of Alexander Dennis and Plaxton, and has over 31,000 vehicles in service in the UK, Europe, Hong Kong, Singapore, New Zealand, Mexico, Canada and the United States. Further information is available at

About Cummins Inc.

Cummins Inc. is a global technology company designing, manufacturing, distributing and servicing a broad portfolio of reliable, clean power solutions; including diesel, natural gas, hybrid, electric and hydrogen fuel cell. Established in 1919 and headquartered in Columbus, Indiana (U.S.), Cummins serves customers in more than 190 countries and territories around the world. More information can be found at