After winning its maiden grand prix in China, Mercedes' form plunged last year.
Eventually the team chose to write off the latter part of the season to make changes to its infrastructure, as the new technical team led by Aldo Costa bedded in.
Despite a disrupted start to 2013 testing at Jerez this week, Mercedes began to get some mileage with Nico Rosberg and Lewis Hamilton on the final days, leaving team boss Ross Brawn optimistic.
"The step we have to make from the end of last year to this year is pretty substantial and it is a moving target as well," said Brawn.
"But what I see at the team as a whole is very encouraging. It's the first [Mercedes] car that Aldo has designed and the aero group seems to be working well, so lots of encouraging signs.
"We know what happened last year, we know what we have to do this year. So we need to quietly get on with it and make sure we don't panic and make sure we do things in the right way."
He added that Rosberg had been able to make reassuring comparisons between the 2012 and '13 Mercedes.
"Nico is obviously the best judge of what we had last year and what we have now and he seems pretty enthusiastic," said Brawn.