Holden is expected to shut down production for several days in the first half of 2013 in response to slow sales.
Prospective Holden buyers are expected to wait until the release of the new Commodore later this year.
"Part of Holden's problem is that they are seeing a buyers' strike ahead of the new model, which is always pretty tough," the AMWU’s Dave Smith told the Herald Sun.
"I think you will see down time. I suspect there will be shorter hours up until the launch of the new car.”
Yahoo!7 predicts that Holden will make big discounts in an attempt to boost sluggish interest in old stock.
Last year Holden cut 370 jobs, and made use of “market response days” to deal with slow demand, with employees at the company’s Elizabeth plant staying home from work on 60 per cent pay.
Meanwhile, the car importer and distributor Saab Australia has been placed in administration, owing $2 million.