MILTON KEYNES (AFP) - Defending Formula One team champion Red Bull on Sunday unveiled the "evolutionary" RB9 car that they hope will carry Sebastian Vettel to an extraordinary fourth double world title this year.
The 25-year-old German became the youngest drivers champion in F1 history last year as he and the team continued their supreme domination for a fourth straight season after resisting the stubborn challenge of Ferrari's Spanish contender Fernando Alonso.
Red Bull technical director Adrian Newey, the boffin behind the brilliance of their cars, said he found it increasingly difficult to create a standard-setting car that set the pace.
Speaking amid the razzamatazz of a futuristic launch for their new purple-coloured machine at their Milton Keynes headquarters, Newey said: "It is increasingly difficult because there are no real regulations changes and it will be the fifth season since the 2009 rule changes.
"The field is converging and you can see how competitive it is in the fact that we had eight different winners last year.
"It's an evolutionary car - there were no big regulation changes over the winter.
"The most significant change is not the regulations, it's the new Pirelli tyres. We had a quick test in P1 in Brazil, but it was very hot and on a green track and in truth we didn't learn a lot."
The champions team will field the same experienced driver line-up this year with Vettel partnered by Australian Mark Webber as they bid to maintain their ascendancy over their rivals.
Newey added: "It's really been a case of refining the RB8. There are no huge changes. It's very much an evolutionary car. All the principles the same as last year.
"The devil has very much been in the detail with this car. We've tidied up some bits that we felt could be improved on. Development is now the key through the year."
The Renault-powered RB9 is the ninth Formula 1 single-seater created by Red Bull since taking over the Jaguar team for the start of the 2005 season.
It will take to the track on Tuesday at Jerez, with Vettel's team-mate Webber doing the initial driving.