Auckland Council is looking to sell or lease its four carpark buildings to help pay its share of the $1 billion blowout in the cost of the city rail loop.
But the Automobile Association is warning of potential price hikes for commuter parking if the parking buildings fall into private hands.
Mayor Phil Goff has pledged to fund the council's $500 million share of the extra cost without raising rates or breaching the council's debt limit - partly by selling or leasing the 4500 carparks in the four inner-city parking buildings.
He said they could raise $100m. But on April 4 SkyCity sold a 30-year concession to operate its 3200 central Auckland carparks until 2048 for $220m, suggesting that 4500 carparks might be worth around $300m.
About half the council's carparks (2088) are in the Downtown building near the waterfront. The others are in the Civic carpark under Aotea Square (1015), Victoria St (888) and Fanshawe St (497).
The four buildings had a book value in 2016 of $224m.
Goff said about $50m from the carpark sale would be earmarked for expanding park and ride facilities serving the rail network and main bus routes.
"We are looking at the sale or concession of some of our non-core commercial assets such as some of our carparks for around $100m, of which half of that we would invest in car park-and-rides," he said.
"Council officers are looking at four carpark buildings in Central Auckland - Fanshawe St, Victoria St, Downtown, and the Civic carpark, where we might be doing what SkyCity has done and letting out a concession for maybe 30 years."
He agreed that selling the parking buildings would reduce future council revenue, but he said it was worth doing to get the money up-front to fund the rail link.