SAO PAULO, Brazil - Sauber has doubled the number of Mexicans on the Formula 1 starting grid by announcing Esteban Gutierrez will step up from reserve driver to the race seat next season.The promotion of the 21-year-old meant Mexico will have two drivers on track in 2013 for the first time since the 1968 Mexican Grand Prix, when Pedro Rodriguez and Moises Solana lined up at the start.MOVING TARGETSGutierrez replaces 22-year-old compatriot Sergio Perez, who is moving to McLaren as replacement for Mercedes-bound Lewis Hamilton, and will partner Germany's Nico Hulkenberg in an all-new lineup.The younger Mexican told reporters at the season-ending Brazilian Grand Prix on Friday: "To be honest, I don't know if I'm ready yet... but definitely I feel I am comfortable to do the next step in my career. "It's important to take it in a very realistic way. Of course I am going to try to adapt as quickly as possible. One of the main goals is to be consistent."It's difficult to say right now or judge how ready I am," continued Gutierrez, who has been racing in the GP2 support series for the past two years."But definitely I'm doing my best and I've been using all the time I have on the track to improve my knowledge of the car, not only the driving itself but also the feedback I can give to the team."Swiss-based Sauber, a solid mid-table team with big Mexican sponsors and close links to Ferrari, has had four podium finishes this season and is sixth overall, 12 points behind Mercedes.Dutchman Robin Frijns, also 21, will take over Gutierrez's role as reserve at Sauber while Kamui Kobayashi, Japan's only current race driver, will be leaving the team.Team principal Monisha Kaltenborn hoped Kobayashi would find somewhere else and recognised the sport could otherwise suffer a backlash in Japan at the absence of a popular driver who finished third in his home race in 2012.Kaltenborn said: "I think that is a risk, especially if you saw how the crowds reacted (at Suzuka) to Kamui's podium and what a great atmosphere there was there. I'm sure it wouldn't have been the case if a Japanese driver hadn't been on the podium."I really hope that he can find the support out there in Japan that he can stay in F1. I think he is definitely a driver that deserves it," she added.Japan, whose manufacturers once played a major part in the sport, no longer has any teams and Nissan's premium brand Infiniti is the sole car maker involved - and that as technology partner to champion Red Bull.Kaltenborn said Kobayashi's departure was not solely down to sponsorship money: "We know him quite well, we had to make this internal decision, we analysed that and we decided to go for two new drivers into next season."