John Banks suffered the indignity of a slow clap while explaining his position on bus lanes at a Super City mayoral debate last night.

The tempo at the Hillary Lecture at Auckland Museum shifted up a notch when questions moved to bus lanes and where Mr Banks was during the "public relations disaster".

The Auckland City mayor rejected the suggestion the bus lanes were a disaster, saying they had been a success in getting people out of cars and into public transport and outlined changes made last week to treat motorists more leniently and fairly and push lawmakers to reduce the $150 fine.

His main Super City leadership rival, Manukau Mayor Len Brown, took the opportunity to tell the audience that Mr Banks set a target to increase revenue from bus lane fines to hold down rates, and that was what people had rebelled against.

When Mr Banks tried to respond, a member of the audience yelled: "You have had your chance, sit down." Others slow-clapped Mr Banks over the issue, which has caused him political embarrassment since revelations that he voted in 2007 to increase income from bus lane and parking fines in order to hold down rates.

Mr Brown's Achilles heel at this election - his use of a council credit card for personal spending - was also raised at the lecture, attended by Sir Edmund Hillary's widow, Lady June Hillary, Dame Jenny Gibbs, acting Auckland museum director Sir Don McKinnon and members of the Museum Circle.

Mr Brown was forced again to admit that he had made four private purchases against the council policy of not using credit cards for personal use, saying it was never his intention not to pay the money back.

"I learned a lot from that experience," said Mr Brown, who saw his big lead in the polls over Mr Banks disappear after his chest-beating, face-slapping response to his council credit card breaches.

A Herald-DigiPoll survey last month showed Mr Brown on 29.6 per cent and Mr Banks, 28.7 per cent.

The performance of the leading contenders also came in for criticism from some of the minor players in the race to be the first mayor of the Super City.

Businessman Colin Craig said he was standing because the old mayors were not delivering.

"If you want the same old thing of rising rates and escalating debt, then don't vote for me," Mr Craig said.

Actor Simon Prast said he did not want to live in an anonymous, dreary, bland, banal, under-achieving place called "Brown Banks" - "that's not the Auckland I grew up in".

"You can say a lot of things about Auckland, but old and tired isn't one of them. To you, Mr Banks and Mr Brown, you have had your turn, your time has come and gone. I think it's time for a new generation of leadership in Auckland," Mr Prast said.