The first national Transport Affordability Index, released by the Australian Automobile Association, whose members include the NRMA, shows a two-car Sydney household faces weekly transport costs of $419 per week.

Sydney households face the highest transport costs of any Australian city both in dollar terms and as a percentage of household income, the report found.

The AAA, which is the peak organisation for Australia's motoring groups and their 8 million members, says it commissioned the report so both consumers and policy makers "have a clear picture of exactly how much transport really costs, and how policy decisions at state and federal levels will affect household budgets over time".

TABLE: Sydney weekly transport costs

Source: AAA

The index is based on the incomes and transport costs of a typical household in each capital city that consists of a couple with children, two cars, and it assumes that one member of the family drives to work, while the other catches public transport. It includes such things as car repayments and tolls but excludes parking costs.

A breakdown of the costs shows that in the average family, loan repayments are the highest typical weekly cost, followed by tolls, fuel, public transport, registration, and licensing.

TABLE: Household total weekly transport costs

Source: AAA

Car repayments cost Sydneysiders on average $120 per week while tolls typically cost $86, fuel $60 and public transport $51.

The cost of transport in Sydney outstrips the other capitals, with Brisbane the next most expensive at $380 a week and Melbourne $352 a week. Weekly transport costs are least in Hobart ($278) and Adelaide ($287).

"Australians know transport is expensive, but they might be surprised to know just how expensive," said Michael Bradley, AAA chief executive .

"The index initially shows around 13 per cent of an average household budget in most capital cities is spent on transport, which is remarkable when you consider that electricity, water, and telecommunications costs account for only one to three per cent of income combined," Mr Bradley said.

The headline figure of $22,000 a year in transport costs is likely to resonate in politically sensitive western Sydney where traffic congestion and access to public transport are routinely hot topics.

While higher density cities such as Sydney, Melbourne and Brisbane report higher costs of transport, the AAA says high incomes in less dense capital cities make transport in those smaller cities significantly more affordable.

The AAA plans to use the index, developed by SGS Economics & Planning, to track the change in costs of transport by analysing tax, tollways, public transport and finance costs as a proportion of average household income.