Safety car
NASCAR
In 2009, NASCAR introduced a new "Double-file restart" rule that lines the field two cars on each row on every restart, similar to the start of the race, instead of lead-lap cars on the outside and lapped cars on the inside. Also, the "wave-around" rule, similar to what is enforced in racing series sanctioned by IndyCar, was adopted to ensure the first car on the restart is the leader, and ensure there are no lapped cars ahead of the leader.
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