The federal government says Labor has misled the public over its claim car maker Holden could have been saved with more taxpayers' money.
But Labor leader Bill Shorten says the coalition has spent more time justifying its inaction than standing up for workers.
Holden plans to pull out of manufacturing in Victoria and South Australia by the end of 2017, but will continue to sell Holden-badged cars made overseas.
General Motors international operations boss Stefan Jacoby told reporters at the Detroit motor show that no amount of extra government funding would have made the plants viable.
"The decision was not made on any (government) incentives or any reduction of incentives," Mr Jacoby said.
Mr Shorten and South Australian Labor Premier Jay Weatherill have insisted Holden - which has made cars in Australia for 75 years - could have been saved with the right incentives.
Treasurer Joe Hockey said on Twitter: "Bill Shorten and Jay Weatherill (have been) called out by GM executives for their foolish behaviour. Enough said."
Coalition frontbencher Christopher Pyne said Labor should apologise for misleading people about public money keeping Holden viable.
"Today we've seen ... the shredding of Jay Weatherill's credibility," Mr Pyne said.
The issue of car making is expected to be key in the SA state election in March as well as the Victorian state election in November.
Mr Shorten told AAP the federal government was treating Australian jobs and workers' livelihoods as a "game".
"They have spent more time trying to justify their own inaction over Holden than they ever spent trying to protect Holden jobs," he said.
"The fact is, the prime minister cares more about his own job than about protecting manufacturing jobs."
Mr Jacoby also said Mr Hockey's declaration in parliament late last year for Holden to "come clean" on its decision had no impact on the outcome.
The car executive said the teleconference in which he proposed the decision - and the board accepted it - was happening at the exact same time.
Acting Greens leader Richard Di Natale said the government was wrong to goad Holden into closing and Mr Weatherill had acted in good faith to stand up for car-making jobs.
Mr Jacoby said car manufacturing generally was not viable in Australia.
Mr Pyne said the government was supportive of the last remaining major car maker, Toyota.
"Of course we want Toyota to stay and we will give them all the support that is available to them under the government's policies," he said.
Mr Weatherill told reporters that the federal government was trying to shift the blame for the demise of Holden in its characterisation of Mr Jacoby's remarks.
He said it remained a fact that in October last year Holden had put a proposition to the commonwealth to retain its manufacturing operations in Australia and the government rejected that proposal.
"Now we have the raking over the coals now Holden has closed to make sure that blame is shifted," Mr Weatherill said.
"A proposition was put to the federal government that they rejected which led to the closure of Holden.
"It's as simple as that."