Vehicle Script Help

I have the following C# script that I am using to allow a player to enter and exit a vehicle, and fire the vehicle’s weapon whilst they are in the vehicle. However, I keep getting the following error code in the Console:
Assets/Scripts/Vehicle.cs(5,40): error CS0119: Expression denotes a ‘type’, where a ‘variable’, ‘value’ or ‘method group’ was expected.

using UnityEngine;
using System.Collections;
public class Vehicle : MonoBehaviour {
	public float bulletSpeed = 10.0F;
	public GameObject projectile = Rigidbody;
	public float getInRange = 6.0F;
	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;
			if (Input.GetKeyDown(KeyCode.Return)) {
				var clone = Rigidbody;
				clone = Instantiate(projectile, transform.position, transform.rotation);
				clone.velocity = transform.TransformDirection (Vector3.forward * bulletSpeed);
			}
		}
		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 < getInRange)
		{
			GUILayout.Label("Press TAB");
		}
		}
	}
	
}

I’m going to say this is your problem. You can’t set a Rigidbody to a Gameobject.

public GameObject projectile = Rigidbody;

If you’re trying to assign the current GameObject Rigidbody to projectile, than you want:

public Rigidbody projectile = gameObject.rigidbody;

unless you want to assign the current Rigidbody GameObject to projectile, then you want this:

public GameObject projectile = rigidbody.gameObject;

Based upon the way you’re trying to Instantiate projectile, I’m assuming you want:

public GameObject projectile;

Then assign a prefab via the Inspector.