Airports face large increases in passengers as Qantas and Virgin step up their battle in the domestic market.

Melbourne airport sucks the most cash out of customers. Photo: Craig Abraham

Brisbane Airport is Australia's most expensive for parking, but Melbourne's Tullamarine sucks the most money from consumers - $114.6 million last financial year.

The competition watchdog's annual survey on how the airports in the five mainland state capitals are performing also reveals that airlines' satisfaction with the quality of service in Melbourne fell more than 20 per cent last year.

The Australian Competition and Consumer Commission chairman Rod Sims stressed, as he released this year's report, that while his commission monitors the airports it has no power to regulate their charges or service levels.

Car parking prices

Car parking prices

"Monitoring does not restrict them from increasing prices, or degrading service standards, to earn monopoly profits," said Mr Sims.

As most airport visitors know from the strain to their wallets, it is parking where they are most in the grip of the airports.

The five airports took in more than $300 million from renting parking spaces last year, keeping $230 million of it as profit.

Melbourne's $87 million carparking profit, aided by the fact that it has 22,400 parking spaces, was more than the combined earnings of Perth, Adelaide and Brisbane.

About one in every five dollars of revenue generated at Melbourne airport comes from parking - easily the highest ratio of any airport in the country.

Sydney airport generates the most money from each of its 12,300 parking spaces - almost $8000 a year, of which $5600 is profit. Brisbane is earning more than $6100 for each spot, and Melbourne is next on $5100.

Brisbane's ranking probably stems from the fact that it charges the highest fees, with a seven-day long term parking space slugging customers $140. In Sydney, a similar stint would set you back $122 and in Perth $88.

On the short-term side, the first hour charge of $15 in Sydney is the most expensive, but Adelaide takes the award for ratcheting up its fees the most. There, the first hour costs only $4, but if you stay for more than 8 hours it costs $30. Melbourne and Sydney's daily parking rates top out at $52.