Nico Rosberg has said that Mercedes made massive improvements in 2012, despite him not scoring a point in the last six races of the season.
The German driver secured his first ever Formula 1 win in the Chinese Grand Prix early in the year.
The 27-year-old told Autosport.com: "The improvement is massive. Unfortunately we haven't seen it much in the second half of the season, but in the first part of the season we had the fastest car in two races - China and Monaco.
"If you would walk through the factory today, you would see a massive improvement compared to three years ago.
"We learned a lot of lessons this year and that's why I'm very confident that we're going to start well next year and then develop through the season."
Rosberg will be joined at Mercedes by Lewis Hamilton in 2013, following Michael Schumacher's retirement.
