Mayoral candidate Len Brown wants to incorporate Waitakere's eco-city into the Super City as part of his plan to build the most liveable city in the world.

Among his environmental goals are a 40 per cent reduction in Auckland's carbon emissions by 2020 and introducing green waste collections.

Speaking to more than 200 Year 13 students at King's College in Otahuhu yesterday, Mr Brown listed the environment with economic growth and building strong communities as his three main goals for the Super City.

The Manukau mayor said he was not only committed to public transport projects - including an inner-city rail loop, rail to the airport and to Orewa - to clear the roads, but to reducing the city's carbon discharges.

"I want to take on board the eco-city concept that the Waitakere community has made its own and incorporate that into Auckland and the Auckland Council's key philosophy," he said.

Mr Brown's willingness to talk policy contrasted with his main rival, John Banks, who told students the election was not about world-class transport or third harbour crossings, but who was the best qualified candidate, with the vision, experience, stability and knowledge to be the first mayor of the Super City.

"I have been a single voice for a greater Auckland," he said. "I'm the only candidate who passionately ... believes that we need a united Auckland. One Auckland, one voice, one songsheet, one song."

Mr Banks said his vision was about investment, growth, jobs and success for the community. His path was one of affordable progress, "not using ratepayers as an ATM machine or council credit card".

"Who do you think is best suited to work with this John Key Government to get resources to build economic infrastructure to make a truly internationally competitive city," said the Auckland City mayor.

Mr Brown said people should not judge candidates on their words, but their actions.

"There is an assertion we will have a strong, collaborative new council," he said. "That is not the experience of Auckland City at all. It has been divided and divisive. The experience of the council I lead has been overwhelmingly of collaboration across political differences."