Bumper in Car

using UnityEngine;
using CnControls;
using System.Collections;

public class skidMarks : MonoBehaviour {
public AudioClip skidSound;
AudioSource skidAudio = null;

public AudioClip bumpSound;
AudioSource bumpAudio = null;
public float bumpMinForce = 4000;
public float bumpMaxForse = 18000;
float bumpMinVolume = 0.2f;
float bumpMaxVolume = 0.6f;

public car car1;

public float minToSlip=150;
public bool rear;
public float skidAt=5.5f;
public float markWidth=0.2f;
public Material skidMaterial;
public GameObject skidSmoke;
public float currentfrictionValue;
int skidding;
Vector3[] lastPos=new Vector3[2];
WheelHit hit;

float force;
float stress;

void Start () {
skidAudio = gameObject.AddComponent<AudioSource>();
skidAudio.loop = true;
skidAudio.clip = skidSound;
skidAudio.volume = 0.25f;
skidAudio.spatialBlend=0.8f;

bumpAudio = gameObject.AddComponent<AudioSource>();
bumpAudio.loop = false;
bumpAudio.clip = bumpSound;
bumpAudio.spatialBlend=0.8f;

}


void FixedUpdate () {
transform.GetComponent<WheelCollider>().GetGroundHit(out hit);
currentfrictionValue=Mathf.Abs(hit.sidewaysSlip);

stress=force-hit.force;
force=hit.force;

BumpPlay (stress);

float rpm = transform.GetComponent<WheelCollider>().rpm;

if((skidAt<= currentfrictionValue) || (rpm<minToSlip && Input.GetAxis("Vertical")>0&& rear) && hit.collider ){
SkidMesh();
if(!skidAudio.isPlaying)
skidAudio.Play();
}
else{
skidding=0;
skidSmoke.GetComponent<ParticleSystem>().enableEmission=false;
skidAudio.Stop();
}
if(transform.GetComponentInParent<Rigidbody>().velocity.magnitude>5){
skidSmoke.GetComponent<ParticleSystem>().enableEmission=true;
}
else{
skidSmoke.GetComponent<ParticleSystem>().enableEmission=false;
}
}

void SkidMesh(){

GameObject mark=new GameObject("Mark");
MeshFilter filter = mark.AddComponent<MeshFilter>();
mark.AddComponent<MeshRenderer>();
Mesh markMesh=new Mesh();
Vector3[] vertices=new Vector3[4];
int[] triangles=new int[6];
if(skidding==0){

vertices[0]=hit.point + Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(markWidth,0.01f,0);
vertices[0]=hit.point + Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(-markWidth,0.01f,0);
vertices[2]=hit.point + Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(-markWidth,0.01f,0);
vertices[3]=hit.point +Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(markWidth,0.01f,0);
lastPos[0]=vertices[2];
lastPos[1]=vertices[3];
skidding=1;
}
else{
vertices[1]=lastPos[0];
vertices[0]=lastPos[1];
vertices[2]=hit.point + Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(-markWidth,0.01f,0);
vertices[3]=hit.point +Quaternion.Euler(transform.eulerAngles.x,transform.eulerAngles.y,transform.eulerAngles.z)*new Vector3(markWidth,0.01f,0);
lastPos[0]=vertices[2];
lastPos[1]=vertices[3];
}

triangles[0]=0;
triangles[1]=1;
triangles[2]=2;
triangles[3]=2;
triangles[4]=3;
triangles[5]=0;
markMesh.vertices=vertices;
markMesh.triangles=triangles;
markMesh.RecalculateNormals();
Vector2[] uvm=new Vector2[4];
uvm[0]=new Vector2(1,0);
uvm[1]=new Vector2(0,0);
uvm[2]=new Vector2(0,1);
uvm[3]=new Vector2(1,1);
markMesh.uv=uvm;
filter.mesh=markMesh;
mark.GetComponent<Renderer>().material=skidMaterial;
mark.AddComponent<destroyAfter>();
}

void BumpPlay(float SuspensionStress){
float bumpRatio=Mathf.InverseLerp(bumpMinForce,bumpMaxForse,SuspensionStress);
if(bumpRatio>0){
bumpAudio.volume=Mathf.Lerp (bumpMinVolume,bumpMaxVolume,bumpRatio);
bumpAudio.pitch=bumpRatio;
bumpAudio.PlayOneShot(bumpSound);
}
}
}