What Is the O'Reilly Auto Parts Series?
The O'Reilly Auto Parts Series is NASCAR's second-tier national touring series, sitting one level below the Cup Series in the NASCAR ladder. Formerly known as the Xfinity Series, the series was rebranded for 2026 after O'Reilly Auto Parts secured the entitlement sponsorship in a deal announced on August 18, 2025.
The series has operated under several names over the decades — the Busch Series, Nationwide Series, and Xfinity Series — but its role has remained consistent: a proving ground for young drivers ascending toward the Cup Series and a competitive home for career series regulars who make their living at this level.
2026 Format
The 2026 season features 33 races split into two segments:
Regular Season: 24 races (February through August) The Chase: 9 playoff races featuring 12 drivers competing for the championship
The Chase Format
The 2026 season introduces a revamped playoff system called The Chase. Key details:
- 12 drivers qualify for the Chase based on regular-season points
- 55 points awarded per race win — wins are heavily rewarded but a single victory no longer guarantees a playoff spot
- The top seed enters the Chase at 2,100 points with a 25-point advantage over second place
- Drivers are separated by 5-point increments down to 12th (2,020 points)
- The Chase culminates at Homestead-Miami Speedway on November 7 for the championship finale
Field Size
The O'Reilly Auto Parts Series typically fields 38 cars per race — larger than the Cup Series field and offering more opportunities for smaller teams to compete.