Red Bull Racing driver and Infiniti Global Ambassador Sebastian Vettel has admitted he doubts he will be able to top the success he has enjoyed in 2011 in future F1 campaigns.

Vettel has taken no fewer than 14 pole positions since the campaign began and stood atop the podium 11 times, allowing him to sail with ease to his second consecutive Driver's Championship. This success has seen Vettel earn countless accolades, as well as lucrative promotional deals with Infiniti luxury cars and others. His triumph has also seen him named as favourite to win a third title in 2012, but Vettel admits that he isn't confident of this with so many other brilliant drivers determined to take the Championship.

"One thing is for sure - such a year doesn't come your way too often," Vettel told the official F1 website. "It was a well-woven tale right from the beginning without a moment of buckling. The car never let us down - and we never let ourselves down. Sure, there were some small issues here and there, but we never ran into a bad-case scenario - nothing like that at all. The major improvement over last season is that we have never been irritated by situations. Even if the boat started to rock we never stumbled - probably something that was not quite there last year.

"There is definitely not one driver I would highlight (as a challenger for 2012) because we are living in a Formula One era where you don't have one challenger but many - with different strengths and weaknesses," he added. "That much I can say. McLaren were very strong this year with both drivers - Jenson and Lewis. It probably wasn't the easiest year for Lewis, but that doesn't mean that this will also go for 2012. Fernando with Ferrari will definitely be there and I also have Mercedes on the list, with two great drivers. And never forget Mark. So I will drop not one name, but many names. That's my opinion."