It may not appear to be the case after two short runs and separate technical issues sidelined Nico Rosberg and Lewis Hamilton on the opening days of the Jerez F1 group test, but the German remains confident that Mercedes can take a step forward in 2013.

Speaking to journalists at the track on Tuesday evening (5 February) - before Hamilton's debut in the W04 was curtailed by rear brake failure on day two - Rosberg said that his first reflections on the new car were positive, despite having been forced to stop his own efforts after just eleven laps on day one as an electrical fault caused it to catch fire. The Mercedes team then cancelled all further activity while it worked on modifying the offending parts before Hamilton's planned outing today (Wednesday).

"My first impressions are very good, very positive," Rosberg commented, "I can guarantee you it will be a big step forward - but, of course, everybody else is also moving forward so we're hoping that we've closed the gap."

Although he claimed his first pole and race win in the top flight at last year's Chinese Grand Prix, Mercedes was no better than fifth in the overall pecking order for 2012, and fell away badly over the final third of the season, with Rosberg not scoring in any of the last six rounds, as development of the car was hampered by its double DRS concept.

"Last year, [the gap] was nearly more than a second, so we have to get closer for sure," he reflected, "and we will get closer. I think [the team has] given us a good base now and it's up to us make the most of it here, find all the problems as we've done today and also improve it and feed back to the factory what are the main things that are still holding us back, what are the main things they need to keep working on."

Expectations will be high following Hamilton's switch from the McLaren team, although the Briton has been playing down his chances of success, claiming that transforming Mercedes into a regular frontrunner was more akin to a marathon than a sprint.

"Improvement can be in being more consistent through the year," Rosberg suggested, "Not like last year where, we started okay and then completely fell off. It would also be a very okay car through the whole season - with a win or two maybe.

"What we need is progress. We need to move forward and go through the season thinking that we are on the right track to become the best."