How to build a car script that allows for car to turn in full circles

So, I need to create a script, that when applied to a game object (it is a rectangle for now, rather than a car) it will allow for the player to move forward and backwards with vertical axis, and when they press and hold to turn left and right (horizontal axis), they can make a full continious circle. What is the best way to go about to doing this? I understand a few concepts, like how there must be a few restriction like a maximum turn angle, maximum speed, but I do not know how to apply this, and how to properly do the math in Unity scripting.

I am a beginner.