McLaren unveiled their 2011 formula 1 car in an unusual ceremony in Berlin, where competition winners turned up with parts of the car and it was assembled before a crowd of photographers.

The new car is strikingly different from its predecessor - with which McLaren came second in the Constructors Championship last year - but the team said it had not given away any secrets by assembling the car before photographers as some of the inner parts were actually plastic mock-ups.

Among the new features are L-shaped sidepods and a double air inlet. The chassis is longer than last year's. The car to be tested next week is expected to feature forward exhausts, not unlike those introduced by Renault on Monday.

Speaking at the launch, former champion Jenson Button said: "I've had some fun years in Formula One - some good, some bad, and I think the competitiveness now is the best it ever has been.

"You have five world champions on the grid but also other drivers who have been close in the past, like Mark Webber or Felipe Massa.

"There is lots of competition and I hope it's a good fight but not too good - hopefully we can have a few tenths on everyone."

Hamilton added: "We should have a more competitive season. We are pushing as hard as we can to be even more competitive than we were last season. I do feel optimistic."

The launch of the MP4-26 was delayed until after the first Formula One tests of the season in Valencia last week, with an interim car used in Spain instead.

Button believes the extra time spent on development will be important, even if it has meant less time actually being able to test the car.

He told autosport.com: "I am sure (other teams) are saying that they have got an advantage because they are driving the new car already, and doing set-up work, KERS work and rear wing work, but I think that for us as a team we understand KERS and that is important.

"I think it was important for us to spend as much time as possible building our car and that when we get it on the circuit it is competitive.

"For us it was the best situation to go to Valencia with the old car and to drive the new Pirellis, and it is good because we can compare the tyres - and you can get lost if there is so much going on."