Multiple qualifying rounds determine the starting grid for most NASCAR national car and truck races for the 2015 season. Different formulas are used depending on the track length.
On tracks of more than 1.25 miles, the starting grid is set after three qualifying rounds. All drivers compete in the first round, and the 24 drivers with the fastest lap times advance to the second round. The remaining drivers are seeded 25th through 43rd based on their best single-lap times.
In the second round, the top 12 drivers advance to the third round. The other drivers are placed 13th through 24th based on their best second-round lap. The format is repeated in the third round with best lap times determining first through 12th in the grid.
On tracks of more than 1.25 miles, two rounds determine the starting grid. The top 12 drivers, based on their best lap time, move to the second round. The remaining drivers are placed 13th through 43th, also based on single-lap times. Second-round lap times determine first through 12th in the grid. Drivers get one timed lap in each round in both formats.
For 2015, NASCAR's national series are the Sprint Cup Series, Camping World Truck Series and the Xfinity Series.