Yes, they're straight diesels. Ironically the model is also available as an electric bus:

https://static1.squarespace.com/static/5318a7c0e4b03ba2018b69f4/t/58ee05af3e00be5228a8a4e1/1491994044902/EvBROCHURE+Mar+2017+UPDATE+-+DIGITAL+VERSION+ONLY.pdf https://static1.squarespace.com/static/5318a7c0e4b03ba2018b69f4/t/58ee05af3e00be5228a8a4e1/1491994044902/EvBROCHURE+Mar+2017+UPDATE+-+DIGITAL+VERSION+ONLY.pdf

Tony P
---InTramsDownUnder@..., <bblunt@...> wrote :

It may have already been mentioned but Tranzit has ordered 114 Optare Metrocity buses for use in Wellington. These appear to be monocoque chassis using Euro6 Mercedes running gear.

Brian