If you've noticed some extremely awkward lap times in your Gran Turismo: HD sessions, that's because the demo came with a bug that went undetected. The bug is that if you end your race right after the time marker past the tunnel marks your time, the game uses that time as your lap time — thus skewing the ranks. Until now, moderators have been deleting these skewed numbers, as they usually pop up and then disappear shortly after. The Japanese PlayStation Network Store received GT:HD V1.1 shortly after the original demo was released, but now the North American store has it too.
So if this bug has been bothering you, delete your original demo download of the game and re-download GT:HD V1.1.