Sebastian Vettel has included the renamed Lotus F1 team amongst those he believes will be challenging his own Red Bull Racing outfit in 2012.

While most predictions group RBR, McLaren and Ferrari - despite the Scuderia's much-publicised struggles in testing - as the expected frontrunners once the 2012 F1 season kicks off in Australia next weekend, the reigning world champion insists that Lotus needs to be watched after a series of impressive performances at Jerez and Barcelona.

Of course, the Enstone squad helped pace last year's pre-season build-up, forcing rivals to consider the merits of its radical side-exiting exhaust, but, having racked up podium finishes in Melbourne and Malaysia, its performance fell away as the development proved less successful than it first appeared.

Vettel, however, believes that the 2012 Lotus is a more potent threat than its predecessor, particularly with the combination of former world champion Kimi Raikkonen and GP2 kingpin Romain Grosjean at the wheel.

"Well, Lotus is back again and they seem to be confirming their performance from the first test in Jerez," the German told the official F1 website during the third and final session at the Circuit de Catalunya at the weekend, before hedging his bets on other possible threats, "Of course, to shine is an integral part of testing and probably some of the usual suspects are holding back a bit. To guess at their real pace is still impossible."

Vettel shared the new RB8 with team-mate Mark Webber for the final two days of testing, admitting that both hoped new parts due to be fitted to the car wouyld confirm its position at the head of the field for a third straight year, but struggled with a wing-breaking off and then gearbox gremlins, restricting his ability to judge the changes.

"If you look up and down the pit-lane, my guess is that everybody else is more or less in the same situation," he replied when asked how close he felt the RB8 was to being an 'ideal' car, "Of course, the last couple of days are quite significant as you get the car closer and closer to what you will be racing, so let's wait and see if we have the right bits and pieces. But, even as we close in towards the car we'll have for the first race - as everybody else also does - it is still hard to say who is quick and who is just playing around with the fuel loads.

"I feel comfortable and that is a good point to start with. Of course there's a loss of grip - the exhaust made a huge difference last season, especially as it was so perfect towards the end - but we will learn to come to terms with it. Sure, the tyres are different too, so this will be something to watch over the first few races - until we get used to it. But, remember, at the same time last year, there was a huge fuss over the new tyres and then in the races everything ran totally smoothly - so never create an issue where there is none!"