NASCAR officials issued technical updates for the 2026 rule book on Friday, including specifics for the Cup Series’ rules configuration for 750-horsepower tracks and a mandate for A-post flaps at every track.
Competition officials announced Oct. 8 that the Cup Series would increase engine output to a target 750 horsepower at tracks measuring less than 1.5 miles in length. Those tracks will use the short-track/road-course rules package introduced to the Cup Series in 2024, with a three-inch rear spoiler and fewer diffuser strakes.
Five tracks will shift from the intermediate-track rules configuration to the short-track/road-course package for 2026: Bristol Motor Speedway, Darlington Raceway, Dover Motor Speedway, Nashville Superspeedway and World Wide Technology Raceway at Gateway.
— NASCAR.com —