UNLESS: you can choose the decade (or even specific year) at which your career starts, and using in-game days, new car models (released on actual days released in reality) become available, (maybe even the same with tracks, though that may be difficult to incorporate) and eventually you see how each race series/type evolves (or even emerges forms [or dies out]) over time. This would require a HUGE amount of classic and retro cars to be modeled (though we have quite a few already), and would likely take an insanely long time to do - but this is a brilliant idea in my opinion, and one that seems realistically huge from a GT standpoint. I'm sure PD could actually pull this off, but maybe not for GT6. It could potentially allow a game that could last an entire console generation, at least at the scale I interpreted it as.