As the sun dipped below the tips of the mountains on the horizon, the asphalt of the Las Vegas Motor Speedway began to glow with the light of fluorescents. Bits of tire surrounded the edge of the track like beaches of rubber sand. Practice was over, and true to its name, Round 6: After Dark began.
Slivers of sunlight remained as the cars gridded up. Drivers took turns boiling their tires before they were paired against their opponents.