在OnTriggerEnter中，检查是否已分配carPlayer或carEnemy，如果已分配，则不执行其余操作：
我还建议加上以下几行：将“刚体.isKinematic = true”和“立方体.变换.SetParent（...）”添加到OnTriggerEnter方法中，因为您不需要每次调用FixedUpdate（）;

public void OnTriggerEnter(Collider collider)
{
    if(_carPlayer || _carEnemy) return; //Check if someone already took control
    if (collider.gameObject.tag == "Player")
    {
        _carPlayer = collider.transform;
        _rigidbody.isKinematic = true;
        _cube.transform.SetParent(_playerParent);
    }
    
    if (collider.gameObject.tag == "Enemy")
    {
        _carEnemy = collider.transform;
        _rigidbody.isKinematic = true;
        _cube.transform.SetParent(_enemyParent);
    }
}

只有当您不希望多维数据集相互窃取时，上面的示例才有效。
如果可以的话，我会建议创建一个1秒的短计时器，在此期间，立方体在有人触摸后无法控制：

public void OnTriggerEnter(Collider collider)
{
    if(timer < 1) return;
    if (collider.gameObject.tag == "Player")
    {
        _carPlayer = collider.transform;
        _rigidbody.isKinematic = true;
        _cube.transform.SetParent(_playerParent);
        timer = 0;
    }

    if (collider.gameObject.tag == "Enemy")
    {
        _carEnemy = collider.transform;
        _rigidbody.isKinematic = true;
        _cube.transform.SetParent(_enemyParent);
        timer = 0;
    }
}

private void FixedUpdate()
{
    if(timer < 1)
        timer += Time.fixedDeltaTime
    ...
}

我会把它统一起来，简单地用一个组件，比如。

public class Car : MonoBehaviour
{
    public Transform CubeParent;
}

在你们两辆汽车。
然后你可以简单地

private Car currentTarget;

public void OnTriggerEnter(Collider collider)
{
    // Someone else was here before already 
    if(currentTarget) return;

    // Otherwise is this even a car at all?
    if(collider.TryGetComponent<Car>(out var car))
    {
        // If so get the parent object we should move to
        currentTarget = car;
        // make this kinematic
        _rigidbody.isKinematic = true;         
    }
}

private void FixedUpdate()
{
    // Only if _cube and currentTarget are both set
    if(_cube && currentTarget)
    {
        // Move the cube towards the target
        _cube.transform.position = Vector3.MoveTowards(_cube.transform.position, currentTarget.CubeParent.position, 0.02f);
        _cube.transform.rotation = currentTarget.CubeParent.rotation;

        // If it reaches the position
        if(_cube.transform.position == currentTarget.CubeParent.position)
        {
            // parent it and forget the cube and target as no longer needed
            _cube.transform.SetParent(currentTarget.CubeParent);
            _cube = null;
            currentTarget = null;
        }
    }
}