French car manufacturer Renault will probably quit Formula 1 if the 'engine freeze' rules are not changed.
That is the claim of Christian Horner, boss of Red Bull Racing, Renault’s work team in F1.
At present, strong rumours indicate Renault is unhappy with its current situation and is looking at buying back the Enstone based team it sold to Lotus at the end of 2009.
But until the end of 2016, supply contracts between Renault and the two Red Bull-owned teams, including Toro Rosso, are set to run.
After that, Horner said in Canada, a failure to change the current restrictions on engine development would be akin to F1 "almost waving goodbye" to Renault.
A complex 'token' system means engine suppliers were able to add performance for 2015, but the amount of allowed development tapers off in 2016 and beyond.
And the 'in-season' development loophole this year has been closed off completely for 2016.
Asked if struggling Renault's rivals, including Mercedes, would agree to change the rules, Horner said: "They don't have to obviously but it is at a precarious point in terms of Renault's commitment to the future.
"If F1 can afford to lose an engine manufacturer, stick to 28 February," he is quoted by the BBC, referring to the current freeze deadline for 2016.