you obviously know nothing about engineering or the process of designing an F1 car, the car was finished way before Frederico got there.
Sorry dude, but as I understand it, the car is developed over a period of months and even years (using technology and knowledge from previous models of cars, to incorporate into the newer cars, albeit bound by a new set of rules and regs).
A driver arrives in the Winter and begins testing, bringing with him his own testing and communication skills. The car usually gets faster as they understand the car better. The team learns how to set the car up better as the months/races role on. Also, new parts are constantly developed, right throughout the season.
Hence, the car is not "finished" before the season starts - its an on-going process of continual improvement, from week to week, month to month and race to race. This is the reason why we see on many occassions, the best car in Race1 isnt necessarily the best car in Race16.