What are the reasons for a driver or team to have to start the race at the rear of the field:
ENGINE CHANGE - anytime during the race weekend [except the Daytona 500, teams can change once after the Gatorade Duel 150's]
BACKUP CAR - after qualifying, if a team/driver goes to a backup car, they start at the rear of the field; if before qualifying and the backup car and engine are presented for inspection, the driver starts where they qualify.
TRANSMISSION CHANGE - anytime during the race weekend [except the road courses, new in 2009]
DRIVER CHANGE - once the car is qualified, if the driver changes, then the driver/car will start at the end of the field before the green flag
