Holden, the maker of the Vauxhall VXR8, stands to lose up to £500million a year from the death of Pontiac.
General Motors has decided to phase out the Pontiac brand by the end of 2010 and with it the G8, which is produced by Holden.
It is estimated that Holden was hoping to export around 30,000 G8s a year to the US, and the Australian car maker has reportedly spent millions converting its factory to build left-hand drive cars.
Overall, Holden hoped to export 70,000 VE Commodores a year, which is the basis for the VXR8 and G8, in a deal worth £500million.
There are already reports of job cut fears in Australia as a result of GM's decision to drop Pontiac.
It is unclear whether there would be any repercussions from Pontiac's axeing in the UK with the VXR8, although Vauxhall hinted that the UK car would not be affected.
One possibility is that the G8 would continue, albeit rebadged as a Chevrolet.