Next year's Formula 1 line-up remains far from certain
Europe's carmakers have joined Formula One's civil war by backing F1's teams in their battle with the sport's governing body over rules and funding.
The European Automobile Manufacturers' Association (Acea) said in a statement that F1's "current governance system (by the FIA) cannot continue."
And it warned a breakaway series could be formed if the objectives of the F1 Teams Association (Fota) are not met.
Acea's stance is being viewed as an attack on FIA president Max Mosley.
The 69-year-old is expected to confirm later this month he will stand for re-election for what would be a fifth term in office.
But in the wake of his bitter battle with Fota over next season's regulations, the Briton's leadership is being questioned.
Acea said: "The FIA needs modernised and transparent governance and processes, including the revision of its constitution.
BBC commentator David Croft explains F1 teams situation
"Acea's members support the activities and objectives of Fota to establish stable governance, clear and transparent rules which are common to all competitors to achieve cost reductions... in order to deliver a sustainable, attractive sport.
"Unless these objectives are met, BMW, Ferrari, Mercedes, Renault and Toyota, along with the other teams, are determined to find an alternative way to practice this sport in a manner which provides clarity, certainty of rules and administration, and a fair allocation of revenues."
Acea's members include BMW, DAF Trucks, Daimler, Fiat, Ford of Europe, GM Europe, Jaguar Land Rover, MAN Nutzfahrzeuge, Porsche, PSA Peugeot Citroen, Renault, Scania, Toyota Motor Europe, Volvo and Volkswagen.
Its statement came on a day when the FIA provoked further controversy with the announcement of next year's line-up, most notably with Ferrari's inclusion against their wishes.
Ferrari have made it clear they have no desire to compete in next year's championship until, in their own words, "the condition of its entry are satisfied".
Red Bull Racing and Toro Rosso have also confirmed their loyalty to Fota, despite the FIA granting them an unconditional entry.
McLaren, Renault, Toyota, BMW Sauber and Brawn GP have been given an extra week's grace to submit their own unconditional entries, otherwise the FIA will return to the pool of potential new entrants.
Fota's main gripe concerns Mosley's governance, and the unilateral manner in which he announced a voluntary £40m budget cap for next season.
On Friday, it sought to bypass Mosley by calling on the World Motor Sport Council and the FIA Senate to intervene in the feud.
In a letter leaked to PA Sport, Fota said it "respectfully seeks the intervention of the World Council to facilitate solutions to the present situation."
It added: "In case this cannot be done, they (the teams) will reluctantly have to seek alternative solutions which protect themselves."
In their own statement, Fota have also threatened to lift the lid on their grievances against Mosley and the FIA.
It read: "Regrettably, Fota is being forced to outline in detail its objections to the new arbitrary FIA proposals.
"We will release details of our concerns in the near future which will constructively explain why the FIA's proposals are bad for the future of F1, the jobs of those employed within the motor-racing industry and the millions of loyal fans who are dismayed and confused at the internal bickering within our sport."
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