That doesn't work. I tried every potential trick (except hiding the MAC address via CFW) and nothing worked. I just ended up taking over my son's GT PSP save for myself as he got bored with the game after a couple of weeks.
There is a little black box on the main menu with a white circle and red dot if you bring your cursor up to that box and hit x it will go to the save screen and save your game but if you have auto save (saves every time you go to the main menu after doing somthing) on this is not required.