Death Mountain is, in some aspects, that. However, majority of the time if you fall off the track, it's game over. I could get behind a map with a style similar to what you're suggesting though, kinda like that one arcade game where you had to rock the ball back and forth up the 'mountain' to win a prize.
I've also been considering game mechanics and trying to figure out a way to make deathrace a little similar to Mario Kart for the Gamecube- anyone on the vehicle, at the time of reaching the finish, wins. I think this can be accomplished with zones and vehicle events, but it will require experimentation.