Aw, so you mean you won all that stuff but lost it right afterwards? That stinks. Did you beat all the time trials or get a 1-star rank on everything? There's some special unlockables if you ever end up doing that.

I ended up finishing the game not too long ago, only to find that the fastest vehicles are still the Flame Runner and Mach Bike.

No, the information is still saved. I just can't play again until we rent the game again. '

I only have the one-star ranking on a few. It took me at least five tries to get my last gold trophy.