advanced car movement script unity

using UnityEngine;using System.Collections; public class CarController : MonoBehaviour {     public WheelCollider WheelFL;    public WheelCollider WheelFR;    public WheelCollider WheelRL;    public WheelCollider WheelRR;     public Transform WheelFLtrans;    public Transform WheelFRtrans;    public Transform WheelRLtrans;    public Transform WheelRRtrans;    public Vector3 eulertest;    float maxFwdSpeed = -3000;    float maxBwdSpeed = 1000f;    float gravity = 9.8f;     private bool braked = false;    private float maxBrakeTorque = 500;     private Rigidbody rb;    public Transform centreofmass;     private float maxTorque = 1000;     void Start ()     {        rb = GetComponent<Rigidbody>();        rb.centerOfMass = centreofmass.transform.localPosition;    }       void FixedUpdate () {      if(!braked){            WheelFL.brakeTorque = 0;            WheelFR.brakeTorque = 0;            WheelRL.brakeTorque = 0;            WheelRR.brakeTorque = 0;        }         //speed of car, Car will move as you will provide the input to it.          WheelRR.motorTorque = maxTorque * Input.GetAxis("Vertical");        WheelRL.motorTorque = maxTorque * Input.GetAxis("Vertical");               //changing car directionHere we are changing the steer angle of the front tyres of the car so that we can change the car direction.         WheelFL.steerAngle = 30 * (Input.GetAxis("Horizontal"));        WheelFR.steerAngle = 30 * Input.GetAxis("Horizontal");    }     void Update()    {        HandBrake();                //for tyre rotate         WheelFLtrans.Rotate(WheelFL.rpm/60*360*Time.deltaTime ,0,0);        WheelFRtrans.Rotate(WheelFR.rpm/60*360*Time.deltaTime ,0,0);        WheelRLtrans.Rotate(WheelRL.rpm/60*360*Time.deltaTime ,0,0);        WheelRRtrans.Rotate(WheelRL.rpm/60*360*Time.deltaTime ,0,0);         //changing tyre direction        Vector3 temp = WheelFLtrans.localEulerAngles;        Vector3 temp1 = WheelFRtrans.localEulerAngles;         temp.y = WheelFL.steerAngle - (WheelFLtrans.localEulerAngles.z);         WheelFLtrans.localEulerAngles = temp;         temp1.y = WheelFR.steerAngle - WheelFRtrans.localEulerAngles.z;         WheelFRtrans.localEulerAngles = temp1;         eulertest = WheelFLtrans.localEulerAngles;    }     void HandBrake()    {        //Debug.Log("brakes " + braked);        if(Input.GetButton("Jump"))        {            braked = true;        }        else        {            braked = false;        }         if(braked){                     WheelRL.brakeTorque = maxBrakeTorque * 20;//0000;            WheelRR.brakeTorque = maxBrakeTorque * 20;//0000;             WheelRL.motorTorque = 0;            WheelRR.motorTorque = 0;         }    }}