IMHO, the cars look better in GT3 (including detail):
Quite nice detail on the road.. and the reflections on the road are stunning.
Check the backlights of the PC car racer, looks pretty bland to me. The overall textures on the cars aren\'t too impressive either. The PC Racer might have impressive AA and high res textures on everything else, but I would want to see how it looks in motion first. GT3 just has lots of effects involved.. realtime reflections on cars
and buildings - the pic you posted just looks.. mmh, different. The detail is imense though, and the PC will always blow consoles away in resolution.
BTW: while we\'re speaking of detail: check the buildings in your pic. Might be colorful and pretty - but it hardly looks better than Ridge Racer V in those terms. GT3 has real time reflections on them aswell... (nicely seen in the Tokyo course).
EDIT: GT3 has problems in some courses which look graphically qiute disappointing. (Like the first screen Fast posted) - those are due to time issues - the other courses like Toyko which look much better clearly prove this.