The Grattan Institute report found up to 40 per cent of car parks were left empty each night in capital city apartments.

Australia is wasting more than $1 billion each year building off-street car parks that end up unused and unwanted, a Grattan Institute report has found.

Parking minimums add $62,000 to the price tag of a two-bedroom Melbourne apartment, $113,000 to one in Brisbane, $137,000 in Perth, and $95,000 in Adelaide.

The report, released tonight, recommends scrapping rules that force developers to include a minimum number of car park spaces when building housing.