NOTE: "Sega GT Homologation Special" is the Japanese Title, the North American version is called "Sega GT". Therefore, the following cheats may only work on the Japanese version since they were listed under "Sega GT Homologation Special" NOT "Sega GT".
Successfully complete each of the official races and event races to unlock the first ending sequence and WSK Races. The WSK Races are the Front Drive Car Cup, Rear Drive Car Cup and 4 Wheel Drive Car Cup.
This trick requires two VMUs. Save the game on both VMUs. Send the cars your acquired from one VMU to the other VMU. Load the game from the VMU with the extra cars. Sell the extra cars for easy money. Repeat as much as desired to have an unlimited amount of money.