From the GT4 US Website, I've been listening to some of the music in the videos. I've kept talking about the themes for the Tune Shop and then the theme for the Tuner Cars. But in some of the other videos on the site, I heard songs such as "Hold the Brakes" (Apollo 440), "Slip and Slide" (A. Skills), "Till the Break of Dawn" (correct title?), and then something from the Pit Crew demonstration that I don't know what it is. Those other three songs I was able to identify can be found within the Environment Element => Dirt and Snow link on the Flash site. I've heard mostly Breakbeat for GT4. Then I've heard of James Brown and Earth, Wind, and Fire remixes in the game. I also noticed some classical music. Maybe it's just me, but 200 mph on the Test Course, listening to something of Mozart's? I... don't know.
I know I'm not a big rock fan, so most of the rock tunes I'll take off of my playlist (there are exceptions in many games I've played). There's five hip-hop songs in the game according to the music list in GT4. It would have been funny to include Ludacris's "Move B****" song in there. It's perhaps the ultimate theme for when you're all p*ssed off and you just want everyone to get out of your way so you can win the race. Then you have Mystikal and I-20 jump in. Disturbing tha' Peace meets New Orleans' Mystikal. Nice mix, I'd say. I heard a nice remix dance remix of "Stand Up" by Ludacris, and that would have been cool for the game.
I hope to get GT4 this weekend and take a listen. Now if you'll excuse me, I have Spring Break to enjoy...