Here is some info i found on Neo-gaf
"Interesting. Lazlow is taking GTA V on a pre-release tour, and letting some radio hosts get their hands on the game. Something extremely similar happened with GTA IV (on the Opie and Anthony show, if I recall). Anyway, it seems some tidbits of information got revealed. Nothing too spoilerific, but it does concern drug use, and some vehicles you can drive:
During the demo, Trevor hijacks a train and 'beats the sh*t out of the conductor'
Each character seems to have their own drug of choice. Michael drinks. Franklin smokes weed. Trevor uses meth. (I'm not quite sure on this one)
Actual LA gang members were recorded for the ambient voices of Los Santos gang members
Each character has their own background score. Trevor's is more 'country', for instance
The graphics are really impressive"
Source