SPIELBERG Austria (Reuters) - Formula One champions Red Bull called for change at engine partners Renault after an 'unacceptable' performance in Sunday's Austrian Grand Prix.
Quadruple world champion Sebastian Vettel retired from the race at Spielberg with an electronics problem, his third failure to finish this season due to an issue with the new V6 turbo hybrid power unit.
"The reliability is unacceptable. The performance is unacceptable. There needs to be change at Renault," team principal Christian Horner told reporters.
"It can't continue like this. It's not good for Renault and it's not good for Red Bull."
The champions, winner of both titles for the past four years with Renault power, are now 158 points behind leaders Mercedes after eight races.
Australian Daniel Ricciardo won the previous Canadian Grand Prix but was a distant eighth on Sunday.
Renault Sport F1's deputy managing director Rob White said the French manufacturer, who started the year well behind Mercedes on performance, knew what had to be done and progress was being made.
"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," he told the Autosport website.
"We know what is expected of us and individually and collectively we must buckle down in the right direction."
Horner made clear Red Bull would stay with Renault next season, when Honda are due to make their return as partners to McLaren, but he wanted to see a big improvement.
The only other engine manufacturers are Mercedes and Ferrari.
"We need to work together as partners. There will not be another engine in the back of the car next year, but we want to be competitive and we want to run at the front," said Horner.
"Something needs to happen because whatever's being done there at the moment isn't working.
"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," added the Briton.
(Writing by Alan Baldwin, editing by Gene Cherry)