Alexander Dennis Enviro500 (3 Door)

The Enviro500 is part of the Enviro series of Dennis low-floor buses which was launched in 2002. The original Enviro500 was produced by Dennis (then known as TransBus International) modified from a Dennis Trident 3 (hence the original name Trident E500).

In late 2003, a face-lifted version was offered; the second-generation Enviro500 (or Enviro500 MkII), featuring both modified chassis and bodywork. The Enviro bodywork was also compatible with the Volvo B9TL chassis, and Kowloon Motor Bus of Hong Kong acquired over 80 such vehicles. From May 2004, when Transbus International was reorganized into Alexander Dennis Limited, or ADL (while absorbing Walter Alexander Coachbuilders and Dennis Specialist Vehicles), future Enviro500s would be marketed under ADL.

Originally offered with the Euro III Cummins ISMe335 (also from the Trident 3), the more environmentally-friendly Cummins ISLe340 option was available in Euro IV and Euro V ratings, relying on Selective Catalytic Reduction (SCR) technology to reduce emissions. Voith or ZF transmissions with SensoTop or TopoDyn fuel-saving features are offered for the Euro V rating. A hybrid electric version (Enviro500H) is also offered, using GM-Allison’s parallel hybrid drive system. Cummins also offers Euro VI-rated engines for newer Enviro500 buses.

In 2012, Alexander Dennis revealed the third-generation Enviro500 aimed at the Hong Kong market. Named the Enviro500 MMC (for Major Model Change), it boasts a new exterior styling adapted from the Enviro400, along with an all-new interior. The new chassis features improved maintainability, reliability and reduced operating costs. New design features included offsetting the longitudinally-mounted engine and gearbox, along with a safer straight staircase and fuel tank underneath the stairs, a design feature adapted from the Enviro400. The chassis was offered in lengths between 11.3m and 13.0m lengths. A rear-axle steering system is also made available, supplied by ZF (Servocom® RAS).

The Enviro500 MMC is also known as the Enviro500NG (for New Generation), Trident E500 Turbo, or simply E50D (with ‘D’ indicating diesel) or E50H (with ‘H’ for hybrid). The Hybrid variant was made available in 2013, incorporating a series hybrid drive-train by BAE Systems (HybriDrive series-E), achieving the Euro VI emission standard.