I'll be having lots of stuff, i'll be doing lots of practise round tracks so i would need a very long playlist.
So i'll take some stuff from previous games (and perhaps some from GT5's default soundtrack too) so thats Feeder, Ash, Cubanate, Dakota Star, Van Halen, Daiki Kasho etc (that alone is probably about 50+ songs)
Then i will be throwing in a mix of other stuff like Queens of the Stone Age, Poets of the Fall, Pink Floyd, Rolling Stones, Audioslave, Jimi Hendrix, Red Hot Chili Peppers, AC/DC anything i have that fits with racing and driving.
I do listen to A LOT of music so i will probably end up with a few hundred songs ranging from soft indie rock to some hard drum and bass.