Sega GT

WSK Races and 1sxt ending:
Finish every official races and event races.
The WSK races include the Front, Rear and 4 wheek Drive Car Cups.

Unlimited money
Note: You need two VMU to do this trick. Save the game on both VMUs.
Transfer the earned cars from VMU 1 to VMU 2. Load back the game
from the VMU with the bonuse cars. Sell all the bonus cars.
Repeat as many times you want.