Unity3D position Update when gameObject is changed

Question

I am trying to make a vehicle changing game where there are 3 gameObject: car, tank and hover and if I press a button to change from car to a tank/hover i want them to be in a position where the car was.

the z axis is forward

I tried this code below but when I go backwards this will not work

UnityEngine;

public class Carswitcer : MonoBehaviour
{
public Transform car;
public Transform hover;
public Transform tank;

void Start()
{
    car.gameObject.SetActive(true);
    tank.gameObject.SetActive(false);
    hover.gameObject.SetActive(false);
}


public void Car()
    {
    
        if (car.position.z < hover.position.z)
            {
                car.position = hover.position;
            }
        if (car.position.z < tank.position.z)
            {
                car.position = tank.position;
            }

        car.gameObject.SetActive(true);
        tank.gameObject.SetActive(false);
        hover.gameObject.SetActive(false);
    }


public void Tank()
    {

        if (tank.position.z < hover.position.z)
            {
                tank.position = hover.position;
            }
        if (tank.position.z < car.position.z)
            {
                tank.position = car.position;
            }
        car.gameObject.SetActive(false);
        tank.gameObject.SetActive(true);
        hover.gameObject.SetActive(false);
    }



public void Hover()
    {

        if (hover.position.z < car.position.z)
            {
                hover.position = car.position;
            }
        if (hover.position.z < tank.position.z)
            {
                hover.position = tank.position;
            }

        car.gameObject.SetActive(false);
        tank.gameObject.SetActive(false);
        hover.gameObject.SetActive(true);

    }   
      

Answer 1

Why compare the z at all? Simply always copy the position of the currently active vehicle:

public class Carswitcer : MonoBehaviour
{
    public Transform car;
    public Transform hover;
    public Transform tank;

    // Store the current vehicle
    private Transform currentVehicle;

    void Start()
    {
        tank.gameObject.SetActive(false);
        hover.gameObject.SetActive(false);

        SetActiveVehicle(car);           
    }

    private void SetActiveVehicle(Transform newActiveVehicle)
    {
        // Is there a current vehicle?
        if(currentVehicle)
        {
            // If so copy its position and set it inactive
            newActiveVehicle.position = currentVehicle.position;
            currentVehicle.gameObject.SetActive(false);
        }

        // Store the new active reference and set it active
        currentVehicle = newActiveVehicle;
        currentVehicle.gameObject.SetActive(true);
    }

    public void Car()
    {
        SetActiveVehicle(car);
    }


    public void Tank()
    {
        SetActiveVehicle(tank);
    }

    public void Hover()
    {        
        SetActiveVehicle(hover);
    }