Sauber's Kamui Kobayashi and Sergio Perez were at the team's base in Hinwil this week for seat fittings in the 'mock-up' of the new Sauber C30.
A brief statement put out by the team added that preparation work for next season is running a 'full throttle'.
"The team around technical director, James Key, is busy with the Sauber C30-Ferrari. The production department has a lot of work to do," added the outfit, which will officially unveil its 2011 challenger in Valencia on January 31.
Perez is now en-route
back to Mexico to spend Christmas with his family, before he moves to Switzerland in January. Kobayashi meanwhile is spending the festive period in his native Japan.