Holden workers in Adelaide who are able to secure full-time employment elsewhere should do so immediately, the Australian Manufacturing Workers Union says.
State secretary John Camillo said 80 per cent of the city's Holden workers had agreed to a final workplace agreement package for an average redundancy payout of $85,000.
He said some employees were already searching for work ahead of the company's closure in 2017 and would receive a reduced payout if they were successful.
"We have in the provision of shutdown the opportunity for people who have found employment to be able to leave at an earlier date," he said.
"They won't get full redundancy, but if you can find full-time employment, I say to people, you should take up the offer now."
The package agreed to by Holden workers equated to four weeks' pay for every year of service, plus four weeks' severance pay.
Mr Camillo said it would be the final package offered to workers before the company withdraws from Australian manufacturing.
"For every 10 people, eight voted for the package, which shows you they were extremely satisfied," he said.
"But people really didn't want to take a package. They wanted to continue working for Holden."
Holden workers will not be the only people affected by the closure of the factory at Elizabeth Vale in northern Adelaide.
Many component suppliers also expected to shut down, along with other associated businesses that have become established alongside the car manufacturing network.
A Workplace Futures Survey that conducted interviews at more than 450 businesses in northern Adelaide this year found about 40 per cent of businesses indicated there was a risk of closure associated with the collapse of the automobile industry.