This is not a full guide but more intended to give you some helpful pointers as to what is required to get 60 points.
There are 5 races in total so you need an average of 12 points per race to get 60 points, meaning that your average placement per race must be 3rd or better. The points given out are as follows:
1st place - 20 points
2nd place - 15 points
3rd place - 12 points
4th place - 10 points
If you finish worse than in 4th place then you should reload an earlier save. Same with if you finish 4th before you know that you can easily get 60 points. I highly encourage you to try to get at least one 2nd place finish in the first two races because things will get hard, very hard.
The first couple of races aren't too bad but from the 3rd and beyond you have to drive practically perfect to even be allowed to finish. I'd recommend making a manual save before each race and then again at every checkpoint where you feel you have driven practically perfect. If you make a save and then later realize that you hadn't driven fast enough, add a "coin" with LB, let the timer expire and press start to continue. You will be back at the start of the race.
A few small tips:
- Turning is very sensitive so any turns with a lower angle than 90 degrees are best to "tap" the stick a few times to get through.
- When the road goes straight up, try to make your car go straight up. There are some roads which go straight up that have jumps and you don't want to hit these jumps at an angle.
- Only use breaking at very steep curves or chicanes. Test what works for you. The person who did the Hi Score guide did not recommend breaking at all but for me, some turns became too hard if I didn't.
- Make manual saves when you feel you have driven perfectly and can do so without being distracted. The last few races require you to be practically perfect so even if you are in 2nd place after a checkpoint you might be screwed if you haven't driven perfectly.
- The car with the best stats is seemingly Thunderjet (bottom row, middle car).
- Practice. This is a hard game and you need to learn the tracks if you want to succeed.