Indianapolis, IN – May 19, 2025
As fans continue to celebrate Josef Newgarden’s thrilling back-to-back victory at the 2024 Indianapolis 500, sharp-eyed observers have turned their attention to a potentially controversial element of his winning Penske-Chevrolet machine: the rear attenuator.
Photos taken inside the IMS Museum, where Newgarden’s car is currently on display, show both sides of the rear attenuator with a notable modification — the seam between its component parts appears to be filled and smoothed, creating a near-continuous aerodynamic surface. This contrasts with the visibly segmented design seen in previous seasons, raising questions about legality and regulatory clarity.
A Seamless Solution, or a Regulatory Slip?
In prior years, such modifications were believed to be outside the scope of legal bodywork under INDYCAR technical regulations, which specify that the attenuator assembly must remain in a stock configuration for both safety and aerodynamic parity. The smoothing of this seam could theoretically provide a slight aerodynamic advantage by reducing turbulent wake from the rear of the car.
“I’m not aware of any rule change in 2024 that would’ve permitted filling or smoothing those seams,” said one veteran race engineer who requested anonymity. “It’s something that would’ve been protested immediately a year ago.”
INDYCAR Silent—for Now
So far, INDYCAR has not publicly commented on the photos or whether the modification had been disclosed, approved, or even noticed during the post-race technical inspection. Given Team Penske’s dominant performance throughout the month of May—and the recent disqualification of all three Penske entries from the St. Petersburg Grand Prix earlier in the season for software-related violations—scrutiny has only intensified.
“Teams walk a fine line,” said racing analyst Jordan Tate. “Aerodynamic development is frozen in many areas, so when you find a legal grey zone, even small changes can be game-changers. But it’s also where things can go very wrong reputationally.”
Technical Advantage or Innocent Oversight?
Experts suggest that smoothing the attenuator seams may have yielded a marginal but valuable decrease in drag or rear turbulence, particularly on a speed-sensitive oval like the Indianapolis Motor Speedway. Whether such a modification crossed the threshold from clever engineering to a breach of technical regulations will likely depend on whether it had been approved through the proper channels.
Some fans and independent engineers are already speculating online, with detailed comparisons between 2023 and 2024 attenuators going viral across social media.
A Call for Transparency
With Newgarden’s win now being examined under a new lens, many in the paddock are calling for INDYCAR to clarify the rules surrounding bodywork modifications—particularly for areas like the attenuator, which are often overlooked but can play an important role in both performance and safety.
Whether this discovery will remain a minor footnote in an otherwise brilliant Month of May, or become a flashpoint for deeper controversy, may depend on what the sanctioning body says—or doesn’t say—in the coming weeks.
