Vettel and Webber unveil 2011 Red Bull car
By Sarah Holt
BBC Sport in Valencia
Sebastian Vettel says it will be harder to defend his Formula 1 title than it was to win it for the first time.
Vettel clinched his maiden drivers' championship last season and helped Red Bull to a first constructors' crown.
"It's a difficult situation because last year we just said 'let's go for the title' - now we want to defend it," said the 23-year-old German.
"It will be a tough battle ahead, a long, hard fight. Motivation is not a problem, but we need to focus again."
Vettel was speaking at the opening day of testing for the 2011 season at Circuit Ricardo Tormo in Valencia, where Red Bull launched their new RB7 car.
According to team principal Christian Horner, it is a vehicle that has had "the shortest build and construction time in our history".
It was unveiled by Vettel and Mark Webber, who finished third in the 2010 standings behind his team-mate and Ferrari's Fernando Alonso.
Red Bull had the fastest package and won nine of the 19 races, but Vettel is fully aware of the task facing his team in an unprecedented 20-race campaign.
"We've a lot of testing ahead of us, a very long season, but we are all pumped and happy to go racing again," he said.
"What we achieved makes us all very proud, and no-one can take it away from us, so that's a huge plus.
"This year is a different story - we have to develop from how we were last year otherwise we will be taking a step back and others will pass us.
"We have to stay focused, try to learn every day, to improve. We have to move forward again."
Relations between Vettel and Webber became strained last year as both men battled hard for a first F1 title.
Webber remained in contention ahead of the season-ending Abu Dhabi Grand Prix, but saw his chance slip by and many felt he would not get a better shot.
However, the 34-year-old Australian was all smiles in Valencia on Tuesday as he prepared to embark on his 10th season in the sport.
There are a lot of things I did right last year, some very proud moments, with 80% of my season in the middle being good. So it's a case of trying to improve on those things, and go for it
"Obviously it was very hard in the middle of a season when we were all achieving some pretty big things to tackle and learn about some of the things that went on," said Webber.
"But as a group we went through a huge amount last year, and we certainly all learned from that. I know I certainly did.
"So the way I am approaching this year is head on again. I've a great opportunity, and a great team around me, to try to improve on what I did last year.
"There are a lot of things I did right last year, some very proud moments, with 80% of my season in the middle being good.
"So it's a case of trying to improve on those things, and go for it."
Horner appreciates that - as the team everyone else wants to beat this term - Red Bull are heading into unknown territory.
"It's a new situation for the team," he said. "The realisation of what we achieved last year is something pretty special for every member of the team.
"But now we're the reigning world champions, and the target is to do our very best to defend both of those titles."
Tuesday also saw Mercedes take the wraps off their new W02 and seven-time world champion Michael Schumacher feels it is the car to get him back on the podium.
The 42-year-old returned to F1 last season after retiring at the end of 2006, but he made little impact as team-mate Nico Rosberg finished 70 points ahead of his fellow German in the final standings.
I am very confident this season we will be standing on the podium much more regularly - ideally in the middle
"Finally the waiting is over and things get started," said Schumacher. "For us drivers the break every year is hard to take because the gap between the last race and the first time out on track seems to be never-ending.
"Even if I have been involved and updated all winter on the developments, and even if I know the improvements are significant, it is still different to see the new car literally for the first time in front of you.
"You automatically build up this nice pre-start tension, so I very much look forward to the new season. We have said it several times already, but again we are really looking to build up something big together.
"I am very confident this season we will be standing on the podium much more regularly - ideally in the middle."
Team principal Ross Brawn believes a closer working relationship between the chassis and engine groups will yield greater dividends.
"The concept development for the car started early and we have set challenging targets for the design, combined with a robust plan to ensure the pace of development can continue throughout the long season," said Brawn.
"We want to be setting the standard right from the start, but if we are not, we will respond very strongly to get ourselves into the game."
Rosberg added: "I am looking forward to having a much stronger season than last year and as always, our targets are aggressive.
"We want to be competing at the front and challenging for race wins. Everyone at our factories in Brackley and Brixworth has worked extremely hard on the new car and we are all looking forward to seeing how it performs."
A third team to launch their new machine on Tuesday was Toro Rosso.
The STR 6 will again be driven by Jaime Alguersuari and Sebastien Buemi and takes into account the requirements set out in the technical regulation changes.
These include the banning of double diffusers, blown rear wings and adjustable front wings - replaced with the arrival of adjustable rear wings and the return of the kinetic energy recovery system (Kers).