Crashes have been a constant part of NASCAR since its inception. As the Cup Series prepares to return to superspeedways, notorious for high-speed chaos, violent wrecks, and cars going airborne, NASCAR has introduced new safety measures for the Next Gen car in 2025.
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On Wednesday, NASCAR updated its rulebook to mandate A-post flaps for superspeedway events, designed to keep cars planted on the track. These flaps, tethered to the car, will make their debut during the Coke Zero Sugar 400 at Daytona International Speedway this August.
The innovation comes in response to a string of frightening flips at Daytona and Talladega in recent seasons. Ryan Preece, who endured a harrowing airborne crash in the 2023 Coke Zero Sugar 400, stands as one of the drivers most affected by such incidents.
The A-post flaps, held in place by magnets and connected to the roof flaps via cables, will deploy in sync with the roof flaps during high-speed spins. Once activated, the A-post flaps will disrupt airflow that causes lift, further reducing the risk of cars flipping. Existing components can be retrofitted to accommodate the new design.
To install the A-post flaps, teams must make two primary modifications to the greenhouse structure: cutting three slots for the tethers and release mechanism, and drilling two holes for 10-32 countersunk fasteners to mount the latch cable block.
While the procedure can be performed with the greenhouse on the chassis, removing it simplifies the process. Proper alignment of the windshield is essential for installing the drill fixture. Both left and right A-posts must be modified.
NASCAR has issued a rules bulletin that includes updates showing the new A-Post flap for use on superspeedways. pic.twitter.com/301HsH5Osa
— Bozi Tatarevic (@BoziTatarevic) July 16, 2025
NASCAR tested the new flaps at the GM Aerodynamics wind tunnel, specifically evaluating the car in yaw. Aero and on-track testing prompted several design tweaks, including a latching system, similar to the rear diffuser flap, to prevent flutter when trailing other cars.
Essentially, the A-post flap is a deployable version of the windshield fin proposed last year, offering the added benefit of staying hidden during normal conditions, thus preserving driver visibility.
Despite the safety intent, many fans remain skeptical, arguing that NASCAR is avoiding the root cause: the flat underbody and diffuser of the Next Gen car. Critics contend these components generate most of the downforce and make cars prone to flipping when turned sideways at high speed.
They also blame the underbody for reduced passing and dirty air, which drivers frequently complain about. One fan remarked, “They sure keep adding a lot of crap to the top of the car when they really need to be talking the crap off the bottom that is causing it.”
Another quipped, “Put a flap here, put a flap there, here a flap, there a flap, everywhere a flap flap. Keep treating the symptoms not the disease.” A third fan bluntly stated, “How about take the flat bottom off,” while another sarcastically asked, “What’s next, the windshield comes up as a flap?”
