Nico Rosberg declares Mercedes quick enough to "annoy" top Formula 1 teams in early 2012 races

Rosberg will not drive the new W03 again until it arrives in Melbourne for the Australian Grand Prix, having completed his two days of testing at Barcelona. But the German is convinced that the team is in a position to improve on its fourth place finish in the 2011 constructors' championship.

"I think we're ready," he said. "It's important for us this year to progress from last year, and we're definitely able to do that. From that point of view I'm pleased, and it's exciting now to go to the first race and see where we are, and finally the talking stops.

"It's still going to be the teams from last year that we need to beat, but I think we have a good chance to annoy them a few times early in the season."

While the Mercedes' tyre degradation is one of the talking points of the test so far, Rosberg shrugged off claims that the car is using its tyres too quickly.

"It's been a positive day, on the longer runs and the shorter runs," he added.

"For the long runs, it's looking okay. No, no concerns. [Degradation] is always a limitation, but it's difficult to know where everyone is. We put in a decent long run today, and we can't really compare. But it's a good base to start off with for us. We're heading in the right direction."

Rosberg also warned that the Barcelona test might not be an accurate barometer for the opening races of the season, with very difficult conditions expected in Australia and Malaysia.

"The thing is that it's very different conditions here to what we'll have in the first few races," he said. "It will be hotter, less grip, and we got caught out a bit last year. Not caught out, but it's just difficult to test well here, and carry everything over.

"You have to be very careful, because a lot of things will just not apply for the first couple of races."