Racer any%

I'm not sure how races are unlocked. I was trying to maximize my bounty in hopes that will unlock races faster, but even after finishing the game I'm not sure.

Cars were chosen at "random" (If one of the cars felt faster I tried to pick it more often)

After looking a little around the internet I've found out that bounty neither unlocking cars unlocks tracks. I suppose there is a sequence that unlocks tracks after every finish.