NASCAR Cup Series teams will compete with a simplified diffuser this season as part of a short track and road course rules package announced on Wednesday.

The updates follow the two-day test at Phoenix Raceway in early December. NASCAR has been experimenting with different packages on short tracks and road courses in hopes of producing better racing.

Details of the updates to the rule book are as follows:

2023 short track/road course splitter stuffers
No engine panel strakes
3-inch spoiler
Simplified diffuser
Simplified diffuser strakes

On the short tracks, the package will be used on at racetracks one mile or shorter with the exception of Bristol Motor Speedway and Dover Motor Speedway. It will not be used in the L.A. Coliseum early next month for the Busch Light Clash.

The package will be run at all five road course races.

“At the test, we noticed an improvement in traffic,” Eric Jacuzzi, NASCAR vice president of vehicle performance said. “The car did not lose rear downforce when it yawed, which is an issue we fight with the current 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.”