Oh, for a car space in the city - on your bike, Clover

IT is the great car park heist and it is costing you dearly in time and money.

It costs $7 an hour to park on a street, $100 a week extra on the rent to park at home, or another $70,000 on the mortgage as authorities thin out basement parking in a bid to "decongest" Sydney.

Sydney City Council's strategy to replace car parks with bike racks had only clogged streets, a new analysis found.

The Decongestion report by peak motoring body NRMA calls on authorities to allow "purpose-built parking to accommodate local needs".

"In Sydney's CBD, motorists can often be seen driving slowly whilst trying to decipher parking signs, or stopping traffic in order to reverse into a parking space, only to then discover that parking is prohibited between certain hours," the report said.

"The same motorists can be spotted circulating around the CBD, adding to congestion, whilst searching for that elusive on-street parking space."

As Sydney Council approves fewer car spaces on unit blocks, the black market is booming with basement spaces rented to city workers for $650 a month.

"You know you live in Sydney when a good car spot will move you to tears," Real Estate Institute NSW CEO Tim McKibbin said.

"For those who are dependent on a car, it is very important to them when they go to buy a property and the costs can be quite substantial. The irony is people's vehicle would often cost less than the spot they are parking it on."

The median price for one bedroom apartments in Sydney in the year to March 2011 was $405,000. Add a car park and it will cost $475,000, Australian Property Monitors data found.

Renters can be asked to pay up to $200 a week more for a one bedroom unit with a car park than one without.

Findacarpark.com.au founder Francis Armstrong said demand forced Sydney's car park rents up to $635 a month - nearly twice the state average.

"Supply is dwindling. Listings in Sydney, if reasonably priced, disappear within six hours. They are posted in the morning and gone by lunchtime," Mr Armstrong said.

Sydney Greens councillor Chris Harris called a 20-unit block with no carparks "ideal" on Monday night but Labor councillor Meredith Burgmann said it was idealistic.

"I know we are trying to stop car use but it is not realistic to think all those people will be living without cars," she said.

"It is car journeys we are trying to stop, not ownership."