Player controlled game object with moving parts?

Hi there!

I am trying to create a player controlled game object that has a part that moves based on velocity. Think of the rear spoiler on a bugatti; as the car speeds up it raises and lowers. As the game object increases in velocity, I want a child part of that object to rotate. I have googled my little fingertips off and cannot get this to work. I used a main parent mesh built in blender and added a rigidbody and tried to transform the game object that was a child mesh of the main parent game object; but I read that that was a bad thing to try to do. It rotates in very odd ways... and it is very jerky.

Should I be using a character controller or a rigidbody for the player controlled object?

Should I be using an animation?

I only used blender to create the shapes; should I be doing something else in blender before importing the prefab?

Can anyone help?