The facelifted version of the Enviro500 body, first built in late 2003, have revised frontal and rear designs.

All KMB's Enviro500s had a bronze band added to the champagne livery to differentiate them from the first-generation low-floor buses.

When TransBus announced the development of the Enviro500, KMB became the launch customer by changing the last 20 of an order for 100 Dennis Trident 3s to the Enviro500 in 2002.

Due to the commencement of the KCR West Rail in late 2003 and KCR Ma On Shan Rail in late 2004, the Transport Department requested KMB to reduce its fleet size, so the registration of these four batches of KMB Enviro500 were delayed and some of them were stored before entering service.

[citation needed] In 2005, KMB ordered a further 25 with modified bodywork and new Alexander Dennis badge, 24 of them (five had their electronic route destination displays supplied by Gorba instead of Hanover) entered service in early 2006.

In late 2005, Long Win Bus ordered five more which had luggage racks fitted when new, entering service in June/July 2006.

Long Win Bus received ten Enviro500 bodywork on Volvo B9TL chassis between 2007 and 2008, one of them was built new as an airport coach.

Due to a surplus in Long Win's fleet, 14 of the Euro IV buses have been transferred to KMB in 2020.

The first batch of chassis arrived Hong Kong in the third quarter of 2007 for body assembly in NWFB depot at Chong Fu Road.

Kowloon-Canton Railway Corporation originally ordered 9 12-metre (39 ft 4+1⁄2 in) Euro IV-engined Enviro500 buses in early 2007 for its Feeder Bus service.

as of December 2024, only three Enviro500s 5550-5552 has finished the conversion process with headlights become identical to the original Alexander Dennis Enviro500 MMCs, being renumbered 59900-59902.

Gyeonggi province test-ran a 79-seat with 12.86-metre long (42 ft 2+1⁄4 in) Enviro500 (North American version) between Seoul and its surrounding cities, which started in mid-November 2014.

[16] A first batch of twenty Enviro500s entered service in December 2005 with Dublin Bus at Donnybrook garage, downsized from what was to be an order of 150 tri-axles.

[17] A further batch of fifty Enviro500s, with a slightly longer front overhang and Euro IV engines, entered service in 2007 at Phibsboro depot.

The American version of the Enviro500 have modified bodies and redesigned fuel tanks, which enable the straight staircase to be moved forward.

Bus operators which evaluated the Enviro500 included Community Transit of Snohomish County, Washington (December 2005), Unitrans of Davis (January 2006, two weeks), OC Transpo of Ottawa (28 June to 12 July 2006 and February 2007), San Francisco Municipal Railway of San Francisco (November 2007 to January 2008)[19] and the Réseau de transport de la Capitale of Quebec City (March 2013).

It was first loaned to Community Transit between 2007 and 2009 which put it into service on 1 August 2007, the bus was used on commuter routes between Seattle and various points in Snohomish County during its first year in operation.

[20] From September 2010, it was loaned to Strathcona County Transit on a one-year lease for the operator's one-year-long double-decker pilot project.

[21] The pilot is part of an exploration of different high-capacity bus types to carry more passengers on the high-demand commuter routes, which are between Strathcona County and Edmonton; an articulated bus is also being evaluated as an alternative and there is no commitment to put any Alexander Dennis model or any double-decker design into permanent service.

[22] In late 2008, Alexander Dennis announced the assembly of the American version of the Enviro500 by ElDorado National in Riverside, California,.

[4] In 2011, Alexander Dennis unveiled a restyled Enviro500 body design for the North American market, which had the same front as the Enviro400.

Both of these batches have a height of 4.2 metres (13 ft 9+3⁄8 in), making them too high to meet bridge clearance (under overpasses etc.)

Numbered from 1201 to 1203, they were operated on a variety of routes, but their height, which exceeded the requirements of the MTO, made them impractical for continued use.

OC Transpo subsequently ordered 75 Go-Anywhere Enviro500s (numbered 8001–8075) for delivery in 2012/13, the first one officially arriving on 23 August 2012.

[24] Strathcona County Transit Strathcona County Transit ordered 14 transit-type Enviro500s (numbered 8001–8014) for their commuter service between Sherwood Park and Edmonton, Alberta, with the first arriving in late 2013 and subsequent buses arriving by the spring of 2014.

[25] They chose double-deckers over articulated transit and motor coaches after a year of testing between September 2010 and October 2011.

They offer extra ventilation grilles outside the engine compartment to cope with Southern Nevada's dry desert climate and high summertime temperatures.

[29] Unitrans (the student-run transit service of University of California, Davis, known for years for its operation of former London Transport double-decker buses) ordered two Enviro500 which were delivered in early 2010; these are the first batch of Enviro500s with the bodywork assembled by ElDorado National.