» Cracks appearing in the RBR-Renault marriage

Following a post-race examination confirming that Sebastian Vettel’s loss of pace (and the win) at the Bahrain GP was in fact due to a faulty spark plug – and not a broken exhaust as originally expected – the focus has now switched back on to Red Bull’s engine supplier, Renault.

The sight of a smoky engine failure for Sebastian Vettel was an all-too-common occurrence in 2009

Having been partnered with the French engine marque since the 2007 season, many felt that the team’s best tilt at the Drivers’ and Constructors’ Championship in 2009 was lost due to the reliability of the Renault engine. Sebastian Vettel, in particular, suffered a string of engine failures and came close to exceeding his 8-engines-per-season cap.

Mark Webber’s RB6 also appeared to suffer a very smoky explosion from its rear end on the opening lap, which caused a collision between Adrian Sutil and Robert Kubica at the first corner.

When asked about the plumes of smoke from Webber’s car, a rather frosty Team Principal Christian Horner said: “Honestly, I have no idea. You have to ask Renault.”

Vettel’s spark plug failure has now cast the relationship between Red Bull and Renault into the shadows, and the team’s motorsport advisor Dr Helmut Marko has also claimed that the team tried to secure Mercedes-Benz engines for the 2010 season, but were blocked by the factory Mercedes GP team.

"They didn’t want us,” Marko said of Mercedes GP. “Without being arrogant, they knew that if we had that engine, they wouldn’t see us [on the track]."

The Austrian also confirmed that Renault had sought permission from the FIA to allow it to equalise its engine performance, with many believing that its engine is some 20BHP down relative to the next-best engine in the field.

Are we expecting to see another engine powering the Red Bull in 2011?