V8 Supercars have drawn the line at no more than five manufacturers in the championship series after Nissan confirmed it would enter and take on Holden and Ford next year.
Nissan will join the series from 2013, with Rick and Todd Kelly's Kelly Racing defecting from Holden to become the Japanese giant's factory-backed team.
And Chrysler is expected to announce in the new few months it will become the fourth make on the grid as V8 Supercars' Car of the Future blueprint allows other manufacturers to join Holden and Ford from next year.
But V8 boss Tony Cochrane said the series needed to be sensible about the number of manufacturers allowed into the sport - saying five was the maximum they would consider.
"We would be very reluctant to go above five manufacturers," Cochrane said in Melbourne today.