Two-time champion Fernando Alonso has warned he could walk away from Formula One if plans to introduce a standard engine for all teams go ahead from 2010.
F1's governing body the FIA has made the engine proposal as one of three options to cut what is views as the sport's excessive costs.
But Renault's double world champion says if they approve a single engine that would be the last straw.
Alonso says it would be time to start thinking about retirement.
FIA president Max Mosley insists F1 must reduce costs by 2010 to stay credible amid a global financial crisis.
But his proposal to introduce a standard engine has met with disapproval from the road-car manufacturers.
Ferrari threatened to review their participation in the sport arguing the use of same engines would deprive F1 of its competition and technological development.