Good luck with that if you want a new car. Car manufacturing is highly automated and so labour costs should not be too high, yet it seems it is not a viable business in Australia. Australian car manufacturing has completely closed down.
Our supermarkets promote their Australian grown vegetables, fish, fruit and meat. This is mostly a good thing. We generally do it better, cleaner and greener than other countries and there is very little that can't be grown here, although we seem to import many tonnes of canned tomatoes from Italy, along with oranges grown in California whereas our orange harvests are often just dumped to rot.
To steal from Hecla, buy Australian. It's good.
With thanks to our Aussie friend Wombat in northern Japan, buy Australian is not new.
The sign sounds racist but not really. That's not to say Australia wasn't terribly racist then. The "Australian Made Preference League Exhibition Touring Train" visited all corners of New South Wales. Buy Australian, Preference Australian made.

The steam engine towed twenty carriages each with a letter on on them making up Buy Australian, the last two carriages being sleeper cars for staff.

There was a very posh dining car attached to the train and local dignitaries wherever the train stopped were invited onboard for dinner before or after grand speeches.

Onboard generators powered the internal electrics and sweeping searchlight type fittings to attract night time attention.
Most days a lecturer left the train and visited local schools to impress upon students the importance of buying Australian.
There were some fabulously lavish and beautiful art work advertising on the train., some of which advertised Nestle products? Yes, Australian made but not where the profits ended up. Get your Jusfrute made with fruit from Gosford, New South Wales.

Ultimately it could be judged as a propaganda train. So what happened to the Buy Australian train? The Great Depression of the late 1920s/30s killed it.