Austrian GP: Red Bull's Christian Horner criticises Renault
Red Bull team boss Christian Horner criticised the performance of engine supplier Renault as "unacceptable" after the Austrian Grand Prix.
Red Bull's home race was their worst of the season - Daniel Ricciardo finished eighth and Sebastian Vettel retired after being delayed by an engine problem.
Horner said: "The situation just isn't improving. The reliability is unacceptable. The performance is unacceptable.
"There needs to be change at Renault. It can't continue like this."
Renault's engine, like Ferrari's, has a significant performance disadvantage to that of Mercedes.
This is helping Mercedes customer teams such as Williams, Force India and McLaren compete with and sometimes beat Red Bull and Ferrari, despite having a less competitive chassis.
Horner said he believed Renault Sport needed to make fundamental changes to its organisation before it could hope to challenge Mercedes.
"Something needs to happen because whatever's being done there at the moment isn't working," Horner said.
"It's not our business; it's not our responsibility. We're the end user and it's just frustrating that it's not where it needs to be at the moment."
Horner said Red Bull would continue with Renault next season but admitted the team were looking at other options beyond that.
However, he dismissed the idea that Red Bull could build their own engine as "highly improbable".
He added: "First of all we need to see what the plans from Renault are. A team like Red Bull isn't short of choices but we want to make sure we're competitive for the long term.
"Obviously designing and manufacturing our own engine isn't currently part of that plan. We have no desire to be an engine manufacturer; we want to work with a strong partner."
Senior executives of the VW-Audi-Porsche Group were guests of Red Bull at the weekend.
Porsche uses an engine in its Le Mans car which uses almost identical technology to the petrol turbo hybrids adopted by F1 this season and could easily be adapted to F1 specification by reducing its capacity.
However, insiders say that a partnership with the VW Group is not likely for Red Bull and that if the German giant did enter F1 in the future, it would most likely be with its own team.
Renault insist they have made some progress with the performance of the engine this year but admit there is a long way to go.
Renault F1 deputy managing director Rob White said: "The anxiety that Christian feels and the frustration he feels after a result that is not at the full potential of the performance of car and power unit is completely understandable and shared by us.
"We are completely committed to making progress as fast as we possibly can and I think we have shown signs of progress before now, and we remain sure of where the expectations of Red Bull and Christian lie."