The Federal Opposition has indicated it will wait until after the election to hold detailed discussions with carmaker Holden about its future in Australia.

Workers at the company's Elizabeth plant at in Adelaide's north will vote on a new pay proposal tomorrow, including a three-year wage freeze, as well as changes to their conditions.

The union representing the workers says the plant could close in 2016 if the proposal is not accepted and more than half must support the secret ballot for the changes to be approved.

Last year, the carmaker was offered a $275 million joint Federal and State assistance package to keep its operations in Australia.

Shadow Treasurer Joe Hockey says that proposal will be look at by the Coalition, should it form government.

"[Holden chairman] Mike Devereux quite wisely said let's see what happens after the election," he said.

"We'll sit down in a considered and measured way and discuss the challenges facing the Australian motor vehicle industry.

"If we're elected into government, we're not going to make rash promises now."

Mr Hockey toured car components maker Multi Slide Industries in Adelaide's south this morning.

The company makes seat frames for the Holden Cruze and Commodore models.

It says its business would be severely reduced if the carmaker closed its door and has expressed concern about the Opposition's plans to reduce funding for the industry.

Managing director Rod Rebbeck says his company's workforce would be halved to about 20 if Holden closed its doors.

He says he would like a Coalition government to reverse its proposal to cancel $500 million in industry funding.

"I would like to see that, but I understand that we're probably living a little bit beyond our means at the moment and I know there has to be some cutbacks, but obviously it's an important part of our business," he said.

The Federal Industry Minister, Kim Carr, has criticised the Coalition's claims that only they can save the automotive industry.

Mr Hockey says the car industry is set to begin an aggressive advertising campaign against the Government's Fringe Benefits Tax changes.

Senator Carr says the advertising does not represent the attitude of all sectors of the industry.

"What we're going to see is an ad campaign by a section of the automotive industry. It's not being supported by the Australian manufacturers. It's being supported by people who organise the leaseholds," he said.

"This is about a group of people that have managed to enjoy the great benefits of the Australian taxation system."