On Friday, NASCAR confirmed multiple technical updates for the 2026 NASCAR Cup Series Rule Book, including specifics regarding the Cup Series’ rule configuration for 750-horsepower racetracks.
In October, NASCAR confirmed that the sanctioning body would be increasing its target horsepower from 670 to 750-horsepower for all NASCAR Cup Series racetracks measuring 1.5-miles in length, or less, in 2026. Those tracks are now all confirmed to be utilizing the short track package.
That short track package, which will expand its reach across five new racetracks for the next season, was introduced in 2024 and features a three-inch rear spoiler and fewer rear diffuser strakes. Those five racetracks include: Bristol Motor Speedway, Darlington Raceway, Dover Motor Speedway, Nashville Superspeedway, and World Wide Technology Raceway.
In addition to changes associated with the upcoming horsepower increase, NASCAR has also mandated that the A-Post flaps are now mandatory for all racetracks in the NASCAR Cup Series, starting in 2026.
The innovation was developed for the regular-season finale at Daytona International Speedway in August, in order to keep vehicles from going airborne and getting involved in violent crashes. After a pair of superspeedway events where the flap worked, NASCAR is making it the lay of the land for all racetracks.
There will also be a slight cosmetic change to the flap, as NASCAR is requiring the fabric underneath to be bright orange, instead of the high-visibility or simply contrasting color that it was required to be in its limited uses at the tail-end of last season.
With RAM set to enter the NASCAR Craftsman Truck Series in 2026, with a five-truck program out of the Kaulig Racing shop, NASCAR has also updated the testing rules for new manufacturers coming into one of NASCAR’s National Series — the NASCAR Cup Series, NASCAR O’Reilly Auto Parts Series, and the NASCAR Craftsman Truck Series.
In each series, the testing guidelines for prospective new manufacturers include a maximum of three tests for new OEMs, with each test limited to a maximum of three affiliated organizations with two vehicles each. The tests must be a maximum of two consecutive days, and by March 1. Those tests cannot be held on racetracks that have been repaved, are new to the schedule, or that will be hosting a race within 60 days of the test session.
As usual, NASCAR’s competition officials expect to release the sporting rules and procedural updates for the 2026 NASCAR campaign in January.