It's almost like Polyphony Digital can't stop adding features. In all honesty, this game could end up being the most complete package ever made. It's almost like a software suite now, rather than a video game.
The latest addition is the weather system. The effects won't be included on every track, but Kaz has stressed it'll likely come into most use on the endurance tracks in combination with the day-night cycle. Being Gran Turismo, the effects are super-super pretty. Check the trailer above and drool.
The game's out in November.