Maybe, I hope it does have damage-able cars and weather.
http://ps2.ign.com/articles/376/376721p1.htmlGran Turismo 4 Details Appear
According to numerous sources, Gran Turismo 4 is well in development and perhaps due for a late 2003 release. It\'s not a surprise, really, since the numbers 4 follows 3, and Gran Turismo 3: A-spec was a roaring success (and for that matter, all of the GT games have been roaring successes).
What we have heard is that the game is about 50% complete, and that Polyphony Digital Lead Producer Kazunori Yamauchi has stated it will feature damage-able car models and realtime weather conditions. If true, the car damage models would be a first for the series and definitely affect gameplay, depending on how much damage the cars actually take (i.e. simple exterior damage versus structural or engine damage). The realtime weather conditions are an extension of the excellent lighting techniques mastered in GT3, and will hopefully include rain, hail, fog, snow and more, though admittedly that\'s pure speculation on our part.