As well as the much-publicised challenges facing Holden and Ford in car sales and manufacturing, they are now under siege in their motorsport heartland.
Nissan's decision to enter the V8 Supercar arena next year shakes up the cosy duopoly that has reigned in Australia's leading motorsport category since the early 1990s.
And there's more to come, with Chrysler poised to enter the series in 2013 as well.
What's now certain is this year will be the last of just Holden versus Ford, with up to five manufacturers on the 28-car grid the magic number V8 chiefs are aiming for.
The welcome mat rolled out for Nissan at a gala launch at Melbourne's Crown Casino on Thursday was a far cry from 20 years ago.
The Japanese giant departed Australian motorsport in 1993 with a size nine up the bumper, Ford and Holden fans waving furious fists and hurling beer cans.
So dominant was the Nissan Skyline GT-R dubbed "Godzilla" throughout 1991 and 1992 that the sport's rules were changed to ban it.
Holden and Ford then got the series to themselves.
In one of those life turns full circle moments, Mark Skaife was the man driving Nissan to dominance.
Now he is the one whose Car of the Future project - the blueprint for V8 Supercars from next year onwards - is opening the door for their re-entry.
Skaife believes Holden - a company for whom he has been the poster boy since Nissan's exit - and Ford have just had that 20-year-old kick up the backside returned.
And he expects the entry of new manufacturers to force Holden and Ford - who have significantly decreased their funding of the sport in recent years - to lift their own game.
"It will bring the re-energising of the incumbent manufacturers," said Skaife, now the V8 Supercar commission chairman.
"There is no doubt when a brand like Nissan comes along, they will do more activation, more leveraging, to support their involvement in the sport.
"If Ford and Holden sit on their hands, they will be beaten."
Nissan's last touring car hurrah came with victory in a rain-shortened Bathurst 1000 in 1992 as a baying mob booed, threw beer cans at the winners' podium, and were famously labelled "a pack of arseholes" by Skaife's co-driver Jim Richards.
But Nissan is confident any road rage towards them as the Skyline battered the Aussie giants has dissipated in the 20 years since.
Car buying patterns suggest they have a point.
We are no longer a nation in love with the big Aussie six.
The Mazda 3 recently displaced the Holden Commodore as the country's No.1 selling car.
Hyundais and Kias, small cars and soft-roaders dot the driveways of middle Australia with far more frequency than the big Aussie sedan or station wagon of old.
And even those cars we've traditionally favoured are being built in non-traditional markets like Thailand and South Africa rather than here.
The reaction to the V8 series' intruders will say much about whether Australian motorsport fans' tastes have changed accordingly.
The Holden-Ford rivalry has arguably been the strongest and most vocal in Australian sport - AFL's Collingwood-Carlton or rugby league's Queensland-NSW on wheels.
It was built through a golden era of touring car racing in the 1970s and early 80s, on icons like Peter Brock, Allan Moffat and Dick Johnson, and the theme has continued throughout the V8 Supercars.
Nissan's entry will be the upwardly-mobile Kelly Racing team, giving them four cars, a solid team of drivers headed by championship-winner Rick Kelly, and a chance to make an immediate impact on the track.
And ultimately Nissan, which has struggled for a share of the Australian car sales market in recent years, is hoping the motor racing mantra of "win on Sunday, sell on Monday" still holds true.
