Null Reference Exception Error

I am adding to the Car Tutorial a particle system that is using the following script. If you take note the script is actually modified from the Pickup script from the 3D Platform Game. I want it so that when the car collides with the particle system, the top speed is increased. This script is added to the particle system. When I run the program, I am getting an error:

NullReferenceException: Object reference not set to an instance of an object
UpdateTopSpeed.OnTriggerEnter (UnityEngine.Collider col) (at Assets/Scripts/JavaScripts/UpdateTopSpeed.js:41)

Does anyone know how to fix this error or how to change the code around so that I don’t have to worry about the error. Note I have not changed much from the tutorial besides adding the particle system and creating this script called UpdateSpeed.

Thank you!

enum PickupType { Health = 0, FuelCell = 1 , TimeCell = 2}
var pickupType = PickupType.TimeCell;
var amount = 1;
var sound : AudioClip;
var soundVolume : float = 2.0;
var carStatus : Car;


private var used = false;
private var mover : DroppableMover;

function Start ()
{
	// do we exist in the level or are we instantiated by an enemy dying?
	mover = GetComponent(DroppableMover);
}

function ApplyPickup (carStatus : Car)
{
	// A switch...case statement may seem overkill for this, but it makes adding new pickup types trivial.
	switch (pickupType)
	{
		case PickupType.Health:
			carStatus.AddHealth(amount);
			break;
		
		case PickupType.FuelCell:
			carStatus.FoundItem(amount);
			break;
			
		case PickupType.TimeCell:
			carStatus.FoundItem(amount);
	}
	
	return true;
}

function OnTriggerEnter (col : Collider) {
	if(mover && mover.enabled) return;
	var carStatus : Car = col.GetComponent(Car);
	carStatus.GetComponent(Car).UpdateSpeed();
	
	//* Make sure we are running into a player
	//* prevent picking up the trigger twice, because destruction
	//  might be delayed until the animation has finished
	if (used || carStatus == null)
		return;
	
	if (!ApplyPickup (carStatus))
		return;

	used = true;
	
	// Play sound
	if (sound)
		AudioSource.PlayClipAtPoint(sound, transform.position, soundVolume);
		
	
	
	// If there is an animation attached.
	// Play it.
	if (animation && animation.clip)
	{
		animation.Play();
		Destroy(gameObject, animation.clip.length);
	}
	else
	{
		Destroy(gameObject);
	}
}

// Auto setup the pickup
function Reset ()
{
	if (collider == null)	
		gameObject.AddComponent(BoxCollider);
	collider.isTrigger = true;
}

If Car is a script and UpdateSpeed() a function of it, you could use this:

    ...
    var carStatus : Car = col.GetComponent(Car);
    carStatus.UpdateSpeed();
    ...

or just this:

    ...
    col.GetComponent(Car).UpdateSpeed();
    ...