To get 20,000,000 Cr. no cheats you just have to do a little work. Try this guide I watched a video of over at ign.
01: First Install 1.01 update.
02: Go to "Vision GT" in Cars Section.
03: Accept the Mercedez Benz Gift Car. It's the first one.
04: Exit the game.
05: Delete the 1.01...