Here is the full list of all 38 Riff Racer - there are Race Your Music achievements.
Score more than 100,000 on a song under 3 minutes in length
Drive 100 songs
Stay in the super-sync zone for 25 consecutive seconds
Jump more than 8 beats in one manoeuvre
Unlock ALL packs
Drive 50 songs
Reach Driver Level 20
Reach Driver Level 15
Reach Driver Level 10
Unlock 20 packs
Drive ALL cars
Drive 10 cars
Play a Hip-Hop/Urban song
Unlock 10 packs
Drift more than 16 beats in one manoeuvre
Reach Driver Level 5
Smash 30 boxes or more without missing one
Play a Pop Song
Play a Classical song
Drive 25 songs
Play a Jazz/Funk/Soul song
Drive 5 cars
Unlock 5 packs
Play a single song 10 times
Author 10 tracks
Drive 10 songs
Author 5 tracks
Beat a friend's ghost
Beat a recommended ghost
Race on a song longer than 10 minutes in length
Enter the super-sync zone 10 times in under 40 seconds
Boost 20 times or more in one song
Drive a whole song without hitting a barricade
Author 1 track
Stay 100% in sync for a whole song
Play a Rock/Metal song
Roll more than 4 beats in one manoeuvre
Play a Dance song