Because Tibbys are popular rice-mobiles and decently fast for that class vehicle.
The Nissan 350Z is in such a whole nother class, though. It would whoop everything else in the screenshots. Too bad they deformed it through poor modelling. It looks like an inline 4 in the game:
http://www.gamespot.com/ps2/driving/nfs ... tml?page=2
They did an awesome rendering job with my car, though:
http://www.gamespot.com/ps2/driving/nfs ... ml?page=65
That is 100% perfect, down to the veilside underbody
But again, the 350Z's only competition is the Supra in this game. Those are the only cars people will drive.
This is what kids do on the street, why would they buy a video game to do it with no thrill?
Atleast you don't have to drive rice in the game:
http://www.gamespot.com/ps2/driving/nfs ... ml?page=44