Hereby my upgrade strategy for the Carrera S.
If I upgrade c.f. this tree the Carrera S is going to cost me 0 GC,
it's practically useless in the Coupe De Disgrace series.
I can only get tot 71% with the Carrera S since I am not going to loose any more GC on that freaking SVR,
so the only use it will have is to drive 2 races in the Porsche Supremacy series and bring the series to 100%.
Maybe the car will apear in new series but it can also be like 90% of the cars eating dust after these 4 available races
(2 in CDD & 2 in PS).
ps: Yes I know it can be done cheaper (earning GC on the car) but I went for speed and acceleration, and this is my max on upgrading. I will try to win the car with only R$ ups.