I'm fairly certain there will be a way to turn off the damage, or minimize its effect, atleast in the beginning on the game.
With GT5 Prologue you could do your bashing techiniques up until the end of the game, the last few races you couldnt slam into cars or hit the wall unless you want additional time added to your lap.
I'm guessing damage may be similar, the further you progress into the game, the more easily you can sustain damage and the greater effect it has on performance.








