The Indy 500 is by far the hardest so far simply because every time you pit, you need to take fuel and tires which makes pitstops over a minute long and thus you need to be a good two laps ahead before you pit. Luckily, the AI takes longer to pit and you'll gain two - 3 laps on them when they pit and a well tuned Minolta easy beat them. I beat everyone by a good 12 laps.