Here's how to get 20 million credits in under 3 minutes. 1.Ensure you have the 1.01 patch installed and at least 1,000,000 credits 2.Buy Mercedes-Benz Concept from GT vision 3.Delete the GT6 game data from the XMB under Game Data Utility (i.e. not the save data) 4.Launch the game and sell this car - now listed as model "2055" - for 333,993,856 credits The game caps your credit count at 20 million credits Credit to Youtuber Radical Dreamer for finding this Source 1 & Source 2