Kyle Busch Rule or Buschwhacker is the system where a Cup Series driver takes part in Xfinity Series or the Truck Series. This is the term that’s used to point out a driver who’s driving both in the top tier and the lower tier in a single season. Brad Keselowski and Kyle Busch are the two notable Buschwhackers.
The Kyle Busch Rule is still in effect as the drivers take part in lower tiers races as well as in the top tier. Also, it should be kept in mind that the drivers with only five or more full Cup Series racing experiences are to be allowed in for multi-series racing.
Apart from taking part in the Cup Series, drivers can still take part in Xfinity and Truck Series. However, the number is as small as five Xfinity Series races and five Truck Series races. The drivers have to have three or more full season experience along with it.