So you have an S13 and you would prefer if you got your own car in game over something would actually be driven and raced?
It will be a stock base model with an additional upgrade most probably but the Nissan Silvia doesn't evoke passion from the factory like the E30 M3 does. That's what Assetto Corsa seems to be about. There are many people still driving stock E30's but I honestly have never seen a stock Silvia of any description in my life.
I'd much prefer to see a time attack style Silvia than a dreary Nissan road car.