Edinburgh is responsible for almost half of the £33.5 million annual profit from parking charges and fines in Scotland, figures show.
New analysis from the RAC Foundation has found that Edinburgh City Council raised £15.3 million from motorists in the Capital in 2013-2014.
This compares to the £10.3m that was made by Glasgow City Council, and £5m in Aberdeen.
Experts at the RAC found that a total of £73.3m was raised across Scotland through parking in the same period.
The combined cost to Scottish local authorities of running parking activities, including the revenue generated from permits and meter payments, was £39.8 million.
This left a profit of £33.5m, up £200,000 on the previous year.
The analysis of the Scottish Government data returned by local authorities prompted calls for councils to be transparent about where the profits are going. It showed that 16 councils made a profit, 13 made a loss and parking operations in the Shetland Islands broke even.
East Lothian and North Lanarkshire councils did not provide a breakdown.
A total of 230,000 penalty charges were issued in Edinburgh over 2013-2014, and it is estimated there were around 700,000 issued across the country.
Professor Stephen Glaister, director of the RAC Foundation, said: “These numbers tell the definitive story of who is making what from public parking in Scotland. Not all authorities are generating a surplus but overall we are talking about big money.
“Nobody wants a parking free-for-all but when we are talking about such large sums, local authorities should be transparent with residents and drivers about what their parking policy is, why charges are set at the level they are and where the profits are going.”
Conservative councillor Joanna Mowat, who represents the city centre ward, described the situation as “frustrating”.
She said the local authority needed to demonstrate that profits from parking charges and fines were being ploughed back into the transport budget.
“It’s how you demonstrate that this is improving roads and pavements, and reducing the maintenance in your car because the roads are better.
“What people see at the moment would make them doubtful as to whether there’s another £15m going in. We should be more accountable to the taxpayer for the money we take from them.”