NASCAR Issues Key Technical Updates for 2026

On Friday, NASCAR issued multiple technical updates for the 2026 NASCAR Cup Series Rule Book, including specifics for the Cup Series’ rules configuration for 750-horsepower racetracks, as well as a mandate for A-post flaps at every racetrack.

NASCAR originally confirmed that it would be increasing the target horsepower from 670 to 750 horsepower in the NASCAR Cup Series for tracks measuring 1.5-miles in length or less for 2026. Those tracks will all be utilizing the short track/road course rules package introduced in 2024, which has a three-inch rear spoiler and fewer rear diffuser strakes.

The result of these changes is five racetracks swapping from the intermediate aerodynamic package to the short track aerodynamic package for 2026: Bristol Motor Speedway, Darlington Raceway, Dover Motor Speedway, Nashville Superspeedway, and World Wide Technology Raceway.

In addition to the changes that are associated with the horsepower increase, NASCAR has also mandated that all NASCAR Cup Series entries have an A-post flap for all racetracks in 2026. The A-Post flap was introduced at the regular-season finale at Daytona International Speedway in August, in order to keep cars from getting off the ground when spinning sideways. The experiment was successful at both Daytona and Talladega.

NASCAR has also implemented a cosmetic change to the A-Post flap, which states that the material underneath the flap must be bright orange, instead of merely a high-visibility or contrasting color.

One unrelated addition to the NASCAR Rule Book ahead of the stretch of the off-season is parameters outlining testing procedures for new manufacturers entering any of NASCAR’s National Series – the NASCAR Cup Series, NASCAR O’Reilly Auto Parts Series, or 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 completed by March 1. Those tests cannot be held at racetracks that have been repaved, are new to the schedule, or that will host a race within 60 days of the test session.

RAM is the only manufacturer new to NASCAR’s National Series in 2026, as the series will join the NASCAR Craftsman Truck Series with a five-truck program from Kaulig Racing. It is unclear what the manufacturer’s testing plan is at this time.

Competition officials expect to release sporting rules and procedure updates in January, as is typical.