The commission will release a report today showing that while the "effective rate of assistance'' for manufacturers is about 4 per cent, and 3 per cent for agriculture, the motor vehicle industry is getting about 9 per cent.
The boost to the car industry came after the Gillard government poured more taxpayer funds into the green car innovation fund and Ford, which will cease its Australian operations in 2016.
The report shows that, overall, $9.4 billion was poured into industry protection in the past financial year and, since May last year, the government has promised a further $430 million in handouts to industry that will be largely spent over the next five years.
The report is likely to reignite political debate over assistance as a new alliance of manufacturing chief executives -- including the Australian-born Andrew Liveris, of US company Dow Chemical -- said industry was "not being mendicant in any way'', and the Coalition reaffirmed its commitment to slashing $500m from car industry subsidies.
Yesterday ,the government defended its assistance to carmakers after Toyota Australia confirmed an after-tax profit of $149.1m for the year to March 31, up from a loss of $13.2m the year prior.
Toyota confirmed that it had received $72m from the Automotive Transformation Scheme and grants in 2012-13, of which some was for a new engine plant under the green carinnovation fund.
The office of Industry Minister Greg Combet said Toyota's financial results reflected not just its local manufacturing operations, but also "significant'' revenues from importing cars to Australia.
"The Gillard government's assistance to Toyota supports its Australian manufacturing operations,'' Mr Combet's spokesman said. "These local manufacturing operations need to compete with other international Toyota subsidiaries for investment from global headquarters.
"The government's assistance is an important ingredient in securing this investment and the jobs that come with it.''
Toyota spokeswoman Beck Angel said the company made a significant contribution to the Australian economy -- injecting about $1.5bn last year -- because of its manufacturing presence, which included local suppliers and wages. "If we do not build vehicles in Australia, this money may be spent in other countries,'' she said.
The commission's annual survey of assistance shows the government gave $5.1bn in budgetary outlays ($400m less than the year prior) and $4.3bn in tax concessions. On top of this, net tariff assistance was worth $1.1bn.
"Assistance generally benefits the industry receiving it and if well targeted and designed, can deliver wider community benefits, but it can also come at a cost to other industries, taxpayers and consumers,'' it says.
In dollar terms, the net combined assistance to the manufacturing sector was $7.35bn, of which $1.1bn went to motor vehicle and parts makers.
This translates into an effective rate of assistance -- a figure that measures assistance as a proportion of the value an industry adds to the economy -- of 4.1 per cent for manufacturers overall and 9.4 per cent for the auto sector.
Opposition industry spokeswoman Sophie Mirabella said the model was "broken and that's a view shared by'' the carmakers.