What is a rear attenuator? Key component behind Team Penske's technical violations explored

Team Penske drivers Josef Newgarden and Will Power have been penalized for illegally modifying their cars during the 2025 Indianapolis 500 qualifying weekend. The issue involved changes to the rear attenuator, a safety part at the back of the vehicle. These changes may have given them a small aerodynamic advantage.

As a result, both drivers have been moved to the last two spots on the starting grid, and team strategists have been suspended. Team Penske has also been fined $100,000 per car and has lost qualifying points and pit box selections.

The rear attenuator plays an important role in both safety and the car's structure. It sits at the very back of the car and is bolted to the gearbox. Its main job is to absorb energy in a crash, reducing the force felt by the driver. It also holds the rain light, which is used for visibility during wet races.

In February 2023, IndyCar introduced a new version of the rear attenuator. Dallara, the series' chassis builder, used improved engineering tools to design a longer and stronger part. The goal was to better protect drivers during rear-end crashes.

A bigger change came in early 2024 when IndyCar required teams to add carbon panels to the inside and outside of the part. These panels had to be glued in place to strengthen the attenuator. Before this rule, the attenuators had a smoother surface.

However, according to Bozi Tatarevic's report on Motorsport.com, some Team Penske members didn’t like how the new glued-on panels looked. A technical leader on the team reportedly asked the crew to clean up the edges, which made the glue less visible. This resulted in smoother edges that may have improved airflow around the back of the car.

A quick look back at the photos of Team Penske’s cars from last season revealed that these modified attenuators were on multiple occasions, including the 2024 Indy 500-winning car of Josef Newgarden. The parts had passed through several rounds of inspections without being flagged.

This case has also raised questions about IndyCar’s inspection system. The modified parts had passed more than a full season of technical checks without being caught.

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Team Penske was caught in a similar technical scandal at the 2024 season-opening race

This is not the first time Team Penske has been caught breaking IndyCar rules. At the 2024 season opener in St. Petersburg, the team faced serious penalties for another technical violation. This time, it involved the push-to-pass system, which gives drivers a temporary boost in horsepower.

By rule, this system cannot be used during race starts or restarts. Josef Newgarden won that race but was later disqualified after officials found out his car had illegal access to push-to-pass. His teammate, Scott McLaughlin, who finished third, was also disqualified for the same reason.

Will Power, who finished fourth, kept his result as he did not use the system illegally but was docked 10 championship points. As per a report by Associated Press, all three drivers were hit with a $25,000 fine.

The problem reportedly began during testing in August 2023, when the team installed a version of the push-to-pass software for hybrid engine development. That version allowed drivers to use the system during starts and restarts.

The team forgot to remove the software before the 2024 season began, which meant their cars had an advantage during the first race. The issue only came to light six weeks later during a warm-up session at Long Beach. A system error turned off push-to-pass for all cars, except the three Team Penske entries, which tipped off officials and led to an investigation.

Once the violation was confirmed, the team accepted the penalties and took action. Team president Tim Cindric and managing director Ron Ruzewski were suspended, as were engineers Luke Mason and Robbie Atkinson. It was the first time in almost 30 years that an IndyCar race winner had been disqualified for a rules breach.