Team principal Christian Horner insists Red Bull are doing their best to close the gap on Mercedes ahead of testing in Jerez Team principal Christian Horner insists Red Bull are doing their best to close the gap on Mercedes ahead of testing in Jerez

Christian Horner has revealed Red Bull are yet to complete their 2015 car, the RB11, and that “there is still plenty to do before Sunday” when the first pre-season test starts in Jerez.

The Milton Keynes-based team were the only team other than Mercedes to win a race last year, but are determined to close the gap to the Silver Arrows this season after seeing their four years of dominance come to an end.

The team have opted not to have a public unveiling of the RB11 prior to Jerez to allow them to maximise production time and, just five days before the first test, their team principal says they are still yet to complete their new challenger.

“No not yet,” Horner said when asked if the car was ready.

“We are flat out into car build at the moment, this is probably the shortest production and assembly time in our 10 seasons – it is unbelievable what the factory have turned around so far. So there is still plenty to do before Sunday.”

However, a Red Bull spokesperson has insisted the former world champions are confident that their 2015 charger will be ready in time for the start of the four-day event in Spain this weekend.

Horner says the RB11’s chassis will be an evolution of that used on the RB10 and that understandably much of their development focus has been on narrowing their engine deficit.

“I think it is just an evolution in many respects,” Horner added. “The chassis is very much an evolution, obviously there has been a lot of focus on the engine and I think with the new regulations and tokens being able to be spent through the year, you have to look strategically and what upgrades you are going to introduce into what engines.

“Mercedes for sure are the benchmark – they go in as the reigning champions and the favourites for this year and they have a significant advantage at the end of last year.

"Hopefully we will have made significant inroads into that advantage, but the question is what have they done over the winter and what have the other teams done? We know where we are, but until you get to Melbourne, or even the first three or four races you won’t really see what the running order is.”

Daniel Ricciardo believes that Red Bull can close the gap on Mercedes in 2015 and can challenge for the title Daniel Ricciardo believes that Red Bull can close the gap on Mercedes in 2015 and can challenge for the title

Rather than having their engines homologated ahead of the first race in Australia, teams will be able to introduce an upgraded engine during the season with the amount of development based on a points system. Horner thinks picking the right moment to introduce those upgrades could be critical in beating Mercedes.

“You can upgrade strategically on your power units this year and Renault are taking an aggressive development approach to this year,” he said. “Strategically we just need to decide when you use those tokens in the four engines that you have available to you."

The Sky Sports F1 Online team will be providing live commentary of all three winter tests, starting in Jerez on Sunday, with live updates from trackside also on Sky Sports News HQ.