i would just model the normal version because of readily available blueprints and just add the gtr crap later, like the front diffuser, hood bulge and wing and all that.

that is already a 3d model in the picture?
i like doing real life cars rather than concepts in order to try and get them as close to real life as possible

btw, the gtr is the only true trim of the nissan skyline and ford is trying to rip it off. ford lives off of ripping off ideas, they even ripped off their own ideas from older years to produce the new mustang....kinda sad, but the car looks not too bad. i still think of ford as the darkside