NASCAR announced Jan. 10 multiple changes to its NASCAR Cup Series rules package for the 2024 season.
The changes cover racing at short tracks and road courses, starting at Phoenix Raceway. They come after testing the series conducted at Phoenix last year. (Despite being a short track race prior to Phoenix, the Busch Light Clash at the Los Angeles Coliseum will not use the changes.)
A simpler rear diffuser is chief among the changes, one that will cut downforce. Conversely, a taller rear spoiler (3 inches, up from 2) will in theory compensate for the decreased downforce.
“One of the things going into the Phoenix test, we said, ‘let’s do a simplified diffuser,’” Dr. Eric Jacuzzi, NASCAR’s vp of vehicle performance, told NASCAR.com. “‘Let’s see what it does when we put it in traffic,’ and what we actually found was it appeared to be an improvement. Then another interesting effect was that it did not lose rear downforce when it yawed, which is an issue we fight with the current car.
“So we felt that the car, the drivers would be able to slide around more on the short tracks and really have to be less careful about putting power down. We felt that would be a benefit, and that was the big takeaway from the driver feedback. At the test, they felt they could really tell that it was more forgiving. They felt they could slide the car, not crazy but certainly much more than they regularly could without having a performance penalty.”
Bristol Motor Speedway and Dover Motor Speedway are not currently included in this change.
NASCAR also announced that cautions at the end of stages on road courses will return in 2024.
Kevin Rutherford is the executive editor of Frontstretch, a position he gained in 2025 after being the managing editor since 2015, and serving on the editing staff since 2013.
At his day job, he's a journalist covering music and rock charts at Billboard. He lives in New York City, but his heart is in Ohio -- you know, like that Hawthorne Heights song.