@Spitty: Thanks, It's viewport shading from new 3DS max 2010. It supports soft shadows and real-time Ambient Occlusion.
@ET: Thanks, I've been improving my skills by modelling something which just needs nice textures, so I did P90 (yes, a sub-machine gun), now you can see results.
@KamikaZ: Thanks but that's from stock Z-tune GTR, I believe that JGTC cars has different underbodies

I'll post template just after finishing UVW, so stay on.
Did some dotails, can't do much more for now cuz I don't have any photos how underbody/rear diffusor could look. I'll maybe start inerior or UVW mapping.
PS attached screen shots w/o viewport shading.