LONDON, England - McLaren has vowed to avoid a repeat of 2011's troubled winter testing as the team unveiled the car which will carry the hopes of Lewis Hamilton and Jenson Button into the 2012 Formula 1 season.Though each is an F1 World champion, Hamilton and Button were left in Sebastian Vettel's slipstream for much of 2011 as the Red Bull driver won a second consecutive Drivers' title.McLaren's failure to mount a sustained challenge has been traced back to poor off-season testing and the team struggling to find a competitive set-up for their car. However the team bosses expect the MP4-27 to be capable of tackling Vettel - and Red Bull - when the 2012 season gets under way.'ABYSMAL' 2011Team principal Martin Whitmarsh said: "We won't know until qualifying in Australia where the car is. Last year we had, by McLaren standards, an abysmal winter testing session where we didn't have pace. It was a relatively stressful process and of course I'd be much happier not fighting those issues."A lot of work has gone into this car and we believe we're in a better position than last winter."Button and Hamilton, who finished second and fifth respectively in 2012, were purring with pleasure at the sight of the new car and are looking forward to testing in Jerez, Spain, next week."It's a very exciting day for us all," Button said. "It's the moment when we see how hard we've all been working. Thanks to the guys who've been working flat-out throughout the winter to develop this car."Testing is now very important. We've got to come out of the box and be strong."SIX CHAMPIONSHamilton also enthused over the new car. "I think it looks fantastic - the most refined-looking we've had for some time, so I'm excited to get back into it."We're coming in hugely motivated, very fresh, and when you have a good-looking car, generally it's a good car - I hope that's the case."Hamilton meanwhile welcomed the prospect of an F1 season that will see six World champions up on the grid. He, Button and Vettel will be joined by Michael Schumacher, Fernando Alonso and Kimi Raikkonen, the most World champions yet to start an F1 season."We love to have competition. It's great to have so many great drivers. I hope there won't be too many more added to it," Hamilton said. "It's great for fans, great for the sport."Whitmarsh brushed off suggestions that Button and Hamilton's intense rivalry could be counter-productive. "We don't like losing or coming second and the last two years have had their frustrations," he said, "but we've two drivers who are fierce competitors, they want to beat each other very badly, yet they spur on each other."