In Gran Turismo 5 for the PS3, the best way to make money is to find the shortest races you can win rather easily to maximize the amount of money you can make.
Keep in mind that these aren’t necessarily a walk in the park. I assume that you’re fairly good at the game, and you have some of the best cars available for your level.
Level 11 and Up – In the Professional Series, do the Daytona Supercar Challenge. It’s a short track taking about two and a half minutes, netting you $17,300 if you get first place.
Level 17 and Up – In the Expert Series, do the High Speed Ring Turbo Challenge. It’s a short track taking about three and a half minutes, netting you $36,000 if you get first place.
Level 22 and Up – In the Extreme Series, do the Rome Circuit on the European Championship. It’s a medium length track taking about five minutes, netting you $83,000 if you get first place.
Level 23 and Up – In the Extreme Series, do the Super Speedway – Indy on the American Championship. It’s a medium length track taking about five minutes, netting you $98,000 if you get first place.