Promoters of a novel car-sharing scheme aimed at discouraging private vehicle ownership want Auckland Transport to follow Sydney's lead in providing free street-parking spaces.

City Hop, which has been struggling for visibility and traction since it was launched in 2007 by the Prime Minister at the time, Helen Clark, is receiving moral support from an Australian scheme with more than 10,000 members.

That compares with City Hop's 350 or so members, who share 25 small and fuel-efficient vehicles on what is generally an hourly hiring basis.

Co-founder Victoria Carter says a big difference is that Sydney's local councils provide almost 500 free street-parking spaces for car-sharing, whereas City Hop is restricted to paid slots with low visibility in Auckland Transport parking buildings.

Economies of scale also allow Sydney's Go Get scheme to offer an hourly fee of just A$5.25c ($6.90c) for regular users, compared with City Hop's $15.

Ms Carter said it had been difficult to persuade Auckland officials to accept car-sharing as an integral part of an efficient transport system, although she was renewing her lobbying efforts following the council-controlled organisation's establishment.

But Auckland Transport communications manager Wally Thomas said that his organisation recognised City Hop as a valuable tool in reducing inner-city congestion and making it easier for people to get around. He was unaware of any proposal to Auckland Transport, but if and when it received one, "we will look seriously at it".

Go Get's chief, Bruce Jeffreys, said during a visit to Auckland that the car-sharing concept was really taking off across the Tasman, to the extent that his company grew by 70 per cent last year.

"Australians are taking to it and they are no different from New Zealanders, so there is no reason it won't take off over here."

Mr Jeffreys said the scheme encouraged people to consider whether they needed a second car when they could perhaps catch trains or buses to work, then hire a vehicle on an hourly basis for errands between times.

He believed high petrol prices helped to focus people's minds on whether they needed to tie up extra resources in a second car, which were often used for unnecessary trips to justify their existence.

But he said that once they joined a car-sharing scheme, they tended to forget how much petrol cost, as vehicle running costs were included in hire fees.

"If you ask our members how much petrol is, most of them don't know - it's not an issue for them," Mr Jeffreys said.

Nor were many particularly interested in what they drove, regarding cars as functional rather than status symbols.

"They are the people who aren't interested in cars - all they want is a new, reliable, clean, safe car to drive."

Mr Jeffreys said his company, which had invested more than A$8 million in its operations, had been provided with 473 free car-share parking spaces in Sydney.