Nice Thread Derail here.
You have you make your A-spec driver commit suicide, obviously.
after you lose about 10 races in a row, your A-spec car driver gets the blues and when you return to main menu you will get a popup message like you got a car and it will say :
'YOU HAVE DIED' All resident evil style. and it will ask you to restart.
Kidding of course....
Real solution:
On XMB go to the Game Tab and open the folder named 'Saved Data Utility (PS3)' and press Triangle on the file named 'GRAN TURISMO 5', (details will say 'Data contains details of your progress through the game.' Should have some details about your save.)
and Press delete.