Ok, maybe not GT4, But they are a NEW GT game that is NOT available to the public, and feature NEW interface and features that will be included in GT4! This is the Lupo Cup Training Disc for Volkswagon, a simulator for their techs or something, and includes 6 NEW tracks;
Tsukuba Circuit
Twin Ring Motegi
Suzuka Circuit (FN/Full Circuit)
CP MINE Circuit
Fuji Speedway
Seeing as though Polyphony have included these into the training disc, you would think it would be very easy to include these into GT4, using the new graphics engine. The Lupo Cup uses an advanced and updated GT Concept graphics engine, not the one that GT4 will use (which is apparently new from the ground up).
Anyway, here are the screens, should give an indication to what GT4 could look like.
In other GT4 news, its rumoured to have 2000+ cars, and feature over 100 tracks! This has been \'confirmed\' by a number of different Japanese sources.