But the chair of Auckland Council's environmental and sustainability forum, Councillor Wayne Walker, said yesterday it was not green enough for his comfort.
"From a sustainability perspective I certainly wouldn't be branding it as a green rig because, you know, it ain't green," he told the Herald.
Even so, he defended the purchase, saying it had plenty of potential for conversion to biofuel and noting that some of its power was already provided by roof-top solar panels.
He said officers had to act fast over the Christmas period to bid for it at "a very good price". Asked if it was a good look using a big diesel rig to try to encourage Aucklanders towards environmental sustainability, he said: "No, it isn't but unfortunately, whether we like it or not, we've got buses and all sorts of stuff that run on diesel, and we have to green that stuff - we have to convert it - and I'll be actively pushing that.
"I'm certainly opposed to calling it the green rig, and it needs to emphasise what it's going to be used for, and that's really education and engagement with a whole raft of council activities," he said.
Despite Mr Walker's belief that the rig was bought at a bargain-basement price, Horizons council member Bob Walker wrote in the Wanganui Chronicle last month that it was "more than most believed we would get for it".
Auckland Council spokeswoman Angela Jones said the vehicle had a "fairly light load by trucking standards", with a gross trailer weight of 15 tonnes and it had travelled only about 50,000km.
Big Rig
Truck: 2006 Mitsubishi Fuso Shogun - six tonnes, six-cylinder diesel intercooled turbo engine compliant with Euro 3 emission standards.
Trailer: 13.9m long, gross weight 15 tonnes. Fibreglass shell over steel frame with aluminium roof and plywood floor.
Features: eight roof-mounted photovoltaic panels generating 1 kilowatt of electricity (equivalent to power use of one-bar heater)