(CNN) -- Nico Rosberg believes Mercedes are on the right track ahead of the new Formula One season following an impressive final day of testing in Barcelona Sunday.
The German driver clocked a fastest time of 1 minute 20.130 seconds to record the best time of any driver over the four-day session, while also eclipsing the times set in the opening week of February.
"I'm pleased with our pre-season testing programme. We have achieved a lot of mileage and I can feel that the balance of the car is good," Rosberg, who put in 131 laps on Sunday, told reporters.
"I have the general feeling that we are in a better position than in the second half of last year but this is testing not racing, of course."
Teammate Lewis Hamilton looked in good shape on Saturday, getting around the track in 1 minute 20.558 seconds, while double world champion Fernando Alonso set a fastest time of 1 minute 20.494 seconds in his Ferrari.
The new season starts in Melbourne on March 17, but Rosberg says conditions in Australia will be completely different to those experienced in the European winter.
He added: "The conditions in the first race will be completely different to here as it will be much hotter in Melbourne and Sepang (the venue of the Malaysian Grand Prix) so we need to wait and see."
Mercedes team boss Ross Brawn believes the hard work put in by his drivers will prove crucial to the team's success in the year ahead.
"I am pleased with the progress that the team has made over the last month and the steps forward that have been made with the car," Brawn told reporters.
"Lewis has settled into the team extremely well and everyone has enjoyed working with both him and Nico throughout the three tests.
"We're realistic about our performance here and our position once we get to Melbourne, and we look forward to the challenge of a new season ahead."