Gran Turismo 5 took eight billion years to make, and it's not finished yet. A new patch is coming that will add "mechanical damage options" to the game. Quite what that means is yet to be elaborated upon, but it will most likely let you toggle the amount of pain you can inflict on your vehicles.
The patch has been pegged for December, so expect it some time in the very near future. According to developer Kazunori Yamauchi, future updates could arrive with more tweaks, such as optional HUD removal, improved cameras and in-game rewards.
Hopefully GT5 is a game that will keep getting better, although according to our own Dale North, there's not a lot of improvement to be had.