GM HOLDEN will seek a taxpayer-funded cash boost of about $200 million to ensure its Adelaide future.

In the wake of warnings its Elizabeth plant is at risk of closure, analysts also have warned that governments must renew investment in research to avoid a cycle of bailouts.

Premier Jay Weatherill refused to reveal how much funding GM requested in talks yesterday in Detroit, but confirmed it was "substantial".

He conceded even the best-case scenario would likely include a cut to its 2500 staff.

Australian Institute for Social Research executive director John Spoehr said political and economic pressures would increase the cost of maintaining the Adelaide plant.

He estimated Holden would demand funding at least equivalent to the $179 million it received to produce the Cruze, in return for guarantees it would build a post-2016 vehicle in Adelaide.

Professor Spoehr said the figure could reach more than $500 million if the State and Federal governments wanted to lock Holden into a deal including several future models over more than 10 years.

Taxpayers also could expect to pay a premium to keep Holden in Adelaide as parent company General Motors faced pressure to protect its US workforce amid a presidential election campaign, he said.

The US-based company was saved from bankruptcy during the global financial crisis by a bailout from President Barack Obama, who is seeking re-election in November.

Emerging Asian economies, such as India, with low labour costs and weak environmental controls also are vying to take production from Australia.

"GM will be in discussion with a range of governments throughout the Asia-Pacific in order to determine what is in their best interests and most profitable outcome," Prof Spoehr said.

He said an Elizabeth closure would be "devastating" for the SA economy and would diminish its capacity to build new manufacturing industries linked to the emerging resources sector.

Speaking to The Advertiser from Detroit, Mr Weatherill said he was intent on not repeating the "Mitsubishi scenario" that ended with its factory closure despite significant taxpayer support.

"We want a sustainable future, not one that's just a stay of execution," he said yesterday.

"We don't want this just to be a rescue package. It's likely that, even if we can secure a future, it will be a future where the industry in South Australia, and Australia, won't necessarily be at its present size."

Mr Weatherill said a funding agreement was possible within weeks, and likely to be contingent on GM increasing use of locally made parts in its global operations.

The Federal Government gave 80 per cent of the Cruze funding and will pay the majority of any future bailout.

The money would pay for more efficient and sophisticated factory machinery to allow construction of new models.

GM Holden chairman Mike Devereux said he was confident of finding "a way forward".

"We are working on a long-term sustainable future for this company," he said yesterday.

"We're talking about things that won't become true until late 2016."

Prescott Securities chief economist Darryl Gobbett said the Federal Government shutdown of its Green Car Innovation Fund last year delivered a blow to the already-struggling sector.

The fund was started to support companies pursuing fuel and greenhouse emission reduction technology and dumped to pay for the Queensland flood cleanup.

"One of the biggest issues that faces the car industry here is volatility of government policy," Mr Gobbett said yesterday.

"If Australia wants to continue on with having a manufacturing car industry here, it's going to have to continue to support research and that capital spend."

He said a support package to sustain the industry for the next decade would likely reach "several hundred million dollars" and include production of hybrid or other hi-tech vehicles.

Opposition Leader Isobel Redmond said it appeared Mr Weatherill had withheld the gravity of concerns over Holden from the public.

"We all want to know how much this is going to cost the state and where on earth they are going to get this money from given the tightness of the Budget," she said.

The Federal Government yesterday gave $34 million as part of a $103 million deal with Victoria to ensure production of the Ford Falcon in Melbourne to the end of 2016.

Originally published as $200m 'needed to keep Holden'