Vehicle Script Modifications

How do I modify this script so that a projectile is emitted from a gameObject when the player presses enter, but only when the player is in the vehicle?

     using UnityEngine;
     using System.Collections;
     public class Vehicle : MonoBehaviour {
         public Camera VehicleCamera;
         public GameObject Player;
         private bool InVehicle;
         private bool VehicleControl;
           public float Speed = 80.0F;
          public float RotationSpeed = 100.0F;
         public Transform _Player;
         private float Distance;
         public Transform _Vehicle;
         private Vector3 VehiclePos;
         void Start()
         {
             VehicleCamera.gameObject.SetActive(false);
         }
         void Update()
         {
             Distance = Vector3.Distance(_Player.position, transform.position);
             if(Distance < 6)
             {
             if(Input.GetKeyDown(KeyCode.Tab))
             {
                 InVehicle = true;
             }
             }
             else if(InVehicle)
             {
             if(Input.GetKeyDown(KeyCode.Tab))
             {
                 InVehicle = false;
                 VehiclePos = new Vector3(_Vehicle.transform.position.x + 5, _Vehicle.transform.position.y, _Vehicle.transform.position.z);
                 _Player.transform.position = VehiclePos;
             }
             }
             if(InVehicle)
             {
                 VehicleCamera.gameObject.SetActive(true);
                 Player.gameObject.SetActive(false);
                 VehicleControl = true;
             }
             else
             {
                 VehicleCamera.gameObject.SetActive(false);
                 Player.gameObject.SetActive(true);
                 VehicleControl = false;
             }
             if(VehicleControl)
             {
             float tr = Input.GetAxis("Vertical") * Speed;
             float rot = Input.GetAxis("Horizontal") * RotationSpeed;
             tr *= Time.deltaTime;
             rot *= Time.deltaTime;
             transform.Translate(0, 0, tr);
             transform.Rotate(0, rot, 0);
             }
         }
         void OnGUI()
         {    if(InVehicle == false)
             {
             if(Distance < 6)
             {
                 GUILayout.Label("Press TAB");
             }
             }
         }
        
     }