Kowloon Motor Bus's purchase of the Enviro500 MMC, officially named Trident E500 Turbo, is the continuation of a long-standing relationship with Alexander Dennis. This New Generation model is an evolution of the original Transbus/Alexander-Dennis Enviro500, which in turn was the direct successor to the Dennis Trident 3. All three models are immensely popular in Hong Kong and saw orders from all three major public bus operators.

KMB's Enviro500 MMC buses are powered by the Cummins ISL8.9e5340B engine (8849cc) which is Euro V compliant and fitted with ZF EcoLife 6AP1700B 6-speed automatic transmission. EDS was supplied by Hanover Displays of the full-LED type. These buses were designated as the ATENU class.

Additionally, KMB has received a 12.8m variant of this model (2 units) for further evaluation.