Speed ​​car at the start of the game

I have a script.

/*
Script Created by FlatTutorials for "Car Controller kit".
*/

@script AddComponentMenu ("FlatTutorials/Scripts/Car Control Script")
#pragma strict
var centerOfMass : Vector3;	//Center of mass
var dataWheel : WheelCollider;	//Wheel Collider from which you want to calculate the speed
var lowestSteerAtSpeed : float = 50;	//if lowestSteerAtSpeed < currentSpeed the steer Angle = highSpeedSteerAngel
var lowSpeedSteerAngel : float = 10;	//This could be a high value
var highSpeedSteerAngel : float = 1;	//This shouldn't be a high value (recomended for stability of car)
var decellarationSpeed : float = 30;	//How fast the car will decellarate
var maxTorque : float  = 50;	//Maximum Torque
var currentSpeed : float;		//Current Speed of car
var topSpeed : float = 150;		//Highest speed at which the car can go
var maxReverseSpeed : float = 50; 	//Highest Reverse speed
var backLightObject : GameObject;	//Mesh for reverse light
var idleLightMaterial : Material;	//for idle state
var brakeLightMaterial : Material; 	//Braked state
var reverseLightMaterial : Material;	//Reverse state
@HideInInspector	
var braked : boolean = false;	//Brake trigger
var maxBrakeTorque : float = 100; 	//Braking speed
var speedOMeterDial : Texture2D;	//GUI Texture for dial
var speedOMeterPointer : Texture2D;		//GUI Texture for needle
var gearRatio : int[];		//Shift gear at speed


function Start () {
rigidbody.centerOfMass=centerOfMass; //Center of mass , for this the car should be pointing on z axis
}

function FixedUpdate () {
HandBrake();
}
function Update(){
BackLight ();
EngineSound();
CalculateSpeed();
}

//Speed Calculation

function CalculateSpeed(){
currentSpeed = 2*22/7*dataWheel.radius*dataWheel.rpm*60/1000;
currentSpeed = Mathf.Round(currentSpeed);
}

//Light Control

function BackLight (){
if (currentSpeed > 0 && Input.GetAxis("Vertical")<0&&!braked){
backLightObject.renderer.material = brakeLightMaterial;
}
else if (currentSpeed < 0 && Input.GetAxis("Vertical")>0&&!braked){
backLightObject.renderer.material = brakeLightMaterial;
}
else if (currentSpeed < 0 && Input.GetAxis("Vertical")<0&&!braked){
backLightObject.renderer.material = reverseLightMaterial;
}
else if (!braked){
backLightObject.renderer.material = idleLightMaterial;
}
}

//Brake Trigger

function HandBrake(){
if (Input.GetButton("Jump")){
braked = true;
}
else{
braked = false;
}
}

//Engine Sound

function EngineSound(){
for (var i = 0; i < gearRatio.length; i++){
if(gearRatio*> currentSpeed){*

break;
}
}
var gearMinValue : float = 0.00;
var gearMaxValue : float = 0.00;
if (i == 0){
gearMinValue = 0;
}
else {
gearMinValue = gearRatio[i-1];
}
gearMaxValue = gearRatio*;*
var enginePitch : float = ((currentSpeed - gearMinValue)/(gearMaxValue - gearMinValue))+1;
audio.pitch = enginePitch;
}

//Speedometer

function OnGUI (){
GUI.DrawTexture(Rect(Screen.width - 300,Screen.height - 150,300,150),speedOMeterDial);
var speedFactor : float = currentSpeed / topSpeed;
var rotationAngle : float;
if (currentSpeed >= 0){
rotationAngle = Mathf.Lerp(0,180,speedFactor);
}
else {
rotationAngle = Mathf.Lerp(0,180,-speedFactor);
}
GUIUtility.RotateAroundPivot(rotationAngle,Vector2(Screen.width - 150 ,Screen.height));
GUI.DrawTexture(Rect(Screen.width - 300,Screen.height - 150,300,300),speedOMeterPointer);

}

How to make a car when you turn on the game itself went forward? Start game = auto speed 100. How to do it?

So you want to create a racing game? If so, this is my answer: