A re-elected Labor government would pump another $500 million into the country's ailing car industry from 2016 to 2020 and hundreds of millions over the subsequent decade.

The commitment is designed to secure the medium-term future of General Motors' Holden operation and the Australian arm of Toyota.

But at least some of the new money will also help keep Ford's research and development plant at Broadmeadows working until the last day of operation at the end of 2016.

The promised new outlays, none of which falls within the current budget period, has been tailored to provide ongoing investment certainty and therefore to protect the jobs of 50,000 auto-sector workers.

However, its short-term target is the electoral loyalty of those workers, many of whom live in outer-metropolitan marginal seats such as Labor-held Corangamite.