Dose any one know how to send object current postion to preivues posistion

You just need to create a Vector3, and store the position, in which this case is a "checkpoint". Something like this would work.

 var checkpoint : Vector3 = Vector3.zero ;
 function Start ( ) { 
    checkpoint = transform.position ;
 }

 //Move the code from start to whenever you want to set this "checkpoint". From there on, you just need to set the position whenever gets hit .
 
 function OnCollisionEnter ( collision : Collision ){
    if ( collision.collider.tag == "EnemyOrObjectName" )
    {
       transform.position = checkpoint ;
    }
 }

Attach that script to your 'car'. Good luck, and I hope this helped.

PS: Please let me know if this does not work for you, and I will approve it, and hopefully others can give some insight on the issue.

~Thanks for using Unity3D.