The technical requirements for cars and drivers are quite simple:
The car must not have any leaks, it must be in one piece, and it must not pose a threat to participants and spectators.
Only the driver may be in the car.
The driver must wear and fasten a helmet, fasten seat belts, and have closed windows.
Every car must have a securely mounted and ready-to-use fire extinguisher.
If you don't have third-party liability insurance (for professional sports cars), you must have your own insurance policy covering you for damage caused to third-party property.