How NASCAR’s Latest Rulebook Tweak Aims to Offer Drivers Enhanced Comfort as Engineers Chase More Speed

NASCAR has introduced a host of new rule changes after the Cup Series race in Atlanta last Sunday. One of the key updates involves the cooling ducts on the front bumper of cars. Going forward, the airflow connections between the rocker box cooling ducts and the exhaust panels must take the most direct route.

This has been mandated to ensure that engineers don’t misuse an apparatus that is in place to reduce heat levels inside the cabin. Engineer Bozi Tatarevic explained on his X handle that NASCAR aims to close a loophole that teams might have found to increase downforce and reduce drag by blocking the airflow.

The cooling ducts direct air through hoses into the rockers and around the exhaust. This makes the rocker box cooler, which, in turn, makes the cabin cooler.

In the Gen 7 era, teams used fans to counteract the airflow through these ducts. However, NASCAR outlawed that when it caught wind of it. Covering the ducts is illegal as well. So, teams got creative with their methods.

Fan rules were instituted in 2022 but teams likely figured out that they could route the hoses in a non-direct way in order to reduce flow through those hoses by adding obstacles and in turn increase front downforce. pic.twitter.com/wOpQH0GCQT

— Bozi Tatarevic (@BoziTatarevic) February 26, 2025

They figured out that routing the hoses in a non-direct way would reduce airflow and increase the downforce. This is why the promotion has written down in the book that the connections ought to be in the most direct route. Notably, the areas near the rocker exceed temperatures of over 160 degrees Fahrenheit.

Other rule changes that have been instituted in the latest update

The Damaged Vehicle Policy came under the spotlight following the mishaps that Kyle Busch encountered in the Daytona 500. He left the designated work area following repairs to his car but came back in again before reaching minimum speed. This led the promotion to declare him retired from the race.

It contended that a driver is allowed to leave the designated work area only once before attempting to reach minimum speed. This mandate was not in the book earlier, but it has now been added.

Changes have also been made to what happens when a driver is not ready to qualify at his designated time. He will be allowed to fall back in line once.

In the scenario that he still doesn’t make it, he will not be allowed to qualify. This slew of changes will be in force from the upcoming race weekend in the Circuit of the Americas.