I have been looking for musics for PolyRace for a long time and I started to make a list of what could be the music of the game. They all fit a fast racing game like PolyRace. The most I like in the playlist is “Drifter” : http://bit.ly/1EfTeaK.
You can find the full playlist on PremiumBeat.com. This online library contains musics but also sound effects. Everything with very high quality. The musics license fee is affordable for an indie dev, it starts a 40$ !