Help with upside-down rotation

TL;DR Here's a video of the issue around the 0:05 mark : https://www.youtube.com/watch?v=YtqWx68WJpQ

I'm just trying to iron out some of the issues I've been running into lately. Not quite sure why the object does a rotation at specific angles, as if it's avoiding crossing certain values or something.

The way I have it set up is that there's a parent which controls the magnetic forces, normal rotation, and other rigidbody forces. On Awake(), a prefab containing the car model and collider is instanced at the origin of the parent.

I'm also running a Cinemachine camera...not sure if that would have any effect on things. If you have any thoughts about this, I'd be happy to hear it!

EDIT: Okay, so I have a few functions that handle rotations:

 void Update()
 {
         //Turning Input
         if (Input.GetAxis("Horizontal") != 0)
         {
             int dir = Input.GetAxis("Horizontal") > 0 ? 1 : -1;
             float amount = Mathf.Abs((Input.GetAxis("Horizontal")));
             Steer(dir, amount);
         }
 
         currentRotate = Mathf.Lerp(currentRotate, rotate, Time.deltaTime * rotSpeed); rotate = 0f;
 }
 
 void FixedUpdate()
 {
         CheckMagnet();
 
         AlignToGround();
 
         Turning();
 }
 
 void Turning()
 {
     //add torque relative to the currentRotate value
         rb.AddTorque(transform.up * currentRotate * Time.deltaTime * rotSpeed);
     }
 
 public void Steer(int direction, float amount)
     {
     //calculate angle from current angle in the left or right direction
         rotate = (steer * direction) * amount;
     }
 
 void CheckMagnet()
 {
 
     //Set the mask layer
         mask = 1 << LayerMask.NameToLayer("TrackMask");
     //Check if there is a track beneath the player
         magnetized = Physics.Raycast(transform.position, -transform.up, out magHit, magnetRange, mask);
 
     //Shoot four rays downwards in four directions
             Physics.Raycast(transform.position + (transform.up * .1f) + (transform.forward * groundCheckDistance), -transform.up, out hitF, magnetRange, mask);
             Physics.Raycast(transform.position + (transform.up * .1f) + (transform.forward * -groundCheckDistance), -transform.up, out hitB, magnetRange, mask);
             Physics.Raycast(transform.position + (transform.up * .1f) + (transform.right * -groundCheckDistance), -transform.up, out hitL, magnetRange, mask);
             Physics.Raycast(transform.position + (transform.up * .1f) + (transform.right * groundCheckDistance), -transform.up, out hitR, magnetRange, mask);
 
     //Calculate the average of the raycast hit normals
                 Vector3 avNorm = (hitF.normal + hitB.normal + hitL.normal + hitR.normal) / 4f;
     //Store the rotation
                 rotateToRoad = Quaternion.FromToRotation(transform.up, avNorm) * transform.rotation;
     }
 
 void AlignToGround()
 {
     //If there is track beneath the player
         if (magnetized)
         {
     //move rigidbody to the hover height
                 rb.MovePosition(Vector3.Lerp(rb.position, transform.up * hoverHeight + magHit.point, hoverSpeed));
     //rotate to the surface normal
                 rb.MoveRotation(Quaternion.Lerp(rb.rotation, rotateToRoad, alignSpeed));
         }
         else
         {
     //Fall with normal gravity and orient self
             rb.MoveRotation(Quaternion.Slerp(rb.rotation, Quaternion.LookRotation(rb.velocity.normalized, Vector3.up), 0.025f));
             rb.AddForce(Vector3.down * fakeGravity, ForceMode.Acceleration);
         }
 }