Mercedes saying no to engine equalisation - Horner

Red Bull continues to rail against the supposed horsepower advantage enjoyed at present by its rivals with Mercedes engines.

After several engine problems last year, the Renault powered team attempted to switch to Mercedes for 2010, but according to Helmut Marko was vetoed not only by the marque's Brackley based works team but also by McLaren.

Instead, Red Bull has applied to the FIA to allow Renault to improve the performance of its engine, but the governing body has declined, insisting that it is instead up to the best engine makers to agree to de-tune their power plants.

"We have 3.5 to 4 per cent less power than Mercedes," Red Bull's team boss Christian Horner told Germany's Auto Bild Motorsport.

He claims there is a 2 per cent performance difference allowed by FIA statutes, adding that Mercedes is "refusing to consent to the equalisation".

But there is a bright side for Red Bull. BBC television's pitlane reporter Ted Kravitz claims Renault has improved its power over the winter, while the French marque's 2.4 litre V8 remains the "most fuel-efficient engine on the grid".

Kravitz cites Williams' technical director Sam Michael as confirming that Mercedes and Cosworth are next best in the efficiency stakes, with Ferrari the most fuel-thirsty engine in F1.

In the new era of no in-race refuelling, it means Sebastian Vettel and Mark Webber are starting Grands Prix in 2010 with 10kg less fuel than the Ferraris, which according to Michael was a nearly ten second weight advantage over the full race distance in Bahrain.