NASCAR Racing: Kurt Busch @brickyard, car rules, backup car

Question
Kurt started 3rd at the Brickyard.  After the first lap he was in the back.  I'm just curious what happened?  I know he had a wreck after he qualified but would he still start 3rd with a differant car and then move to the back?  Help I'm confused.

Answer
Since he was unable to fix the car that he qualified he had to start a "back up" car. Rules state that if a backup car is used the car must start at the back of the field.

So what happens is as the cars pull off the pit lane at the beginning of the race Kurt pulls out in 3rd then pulls to the side of the track and lets everyone go by. When they throw the green flag at the start of the race he must be at the back of the pack.