[Unity3D] How to make Race Standings or Position ?

Hello everybody, I'm making a racing game project. I have a question on making Race Standings or Position. You know, it's like this



I've searched all around google and it still doesn't help. I've also tried all my method to make this thing works.

I've tried

• Who is nearest to the Waypoint, it’s the lead. But it was failed, because i can’t figure it out how to make the player knows its ranking.
  
• Activate when a player hits a triggered box collider and then check if the player which is just hit the line is in front of me, the player rank was +1, and otherwise if the player which is just hit the line is in my behind, i was +1. But i don’t use it because all player thinks they are number 1.
  
• Use Vector3.Dot to check the distance to other player. Not used because of complexity.
  
• Who is fastest to the waypoint its the lead. It’s record time you reached the checkpoint and compare it to other. The Reason i don’t want to use this because, i can’t figure it out how to make the player knows its ranking.
  
• Each AI Shoots ray to waypoint. AI Distance value send to all waypoint. Then Waypoint sort the distance. From AI kart, find a distance that has same value with waypointer, and then the waypointer returns it length.
  
• Use SphereCollider Is Trigger to check distance. But the AI doesn't work properly when i do this.

Do you know a method that works to make a race standings ? please help me. This code making me crazy.

Thanks for any help