witch approach for an car race curve

i hope someone can help me, i’ll make a simple racing game where you don’t control the car directly, you just are able to turn the car when a button is pressed, ( for sure you have to press the button in a specific zone to make it turn in the right way) here is the point, i have different curve in a multiple form and before the curve there is this “brake point”,
i’ll pasta here a simple picture that i did to make it more clear

turning point is dynamic
i’ll do it everything by code without any kind of rigidbody or collider, ( i have to practice with coding so that’s why)

any advice to how do that?

If I understand correctly, you want the car to turn only if a button it’s pressed when in a predefined position in the curve. The most simple solution would be making an empty object with a triggered collider. If the car it’s inside the trigger and you press the button, you turn. Very straightforward.