Alex Palou Puts New IndyCar IR-28 Chassis Through First Sebring Stress Test

Reigning NTT INDYCAR SERIES champion Alex Palou completed 43 laps on the outer loop at Sebring International Raceway, putting the new IR-28 chassis through its first major physical test away from the Indianapolis Motor Speedway, indycar.com reported. The evaluation on Monday followed initial August and September tests on the smooth asphalt of IMS, moving the development car directly into punishing, rough-surface conditions designed to stress structural durability.

Putting the IR-28 Through Sebring Stresses

Sebring serves as a critical proving ground for INDYCAR teams due to its combination of abrasive asphalt and concrete surfaces alongside deep, jarring bumps. This layout intentionally replicates the aggressive conditions found on temporary street circuits, which accounted for one-third of the 2026 schedule. According to indycar.com, the circuit tests component strength better than almost any other venue on the calendar.

Palou explained the objective of the punishing run to indycar.com, noting that the team wanted to test the car as hard as possible before production begins. Engineers and drivers are accumulating high mileage to identify vulnerable areas. Palou and 2016 Indianapolis 500 winner Alexander Rossi remain the sole drivers entrusted with testing the chassis ahead of its planned 2028 debut.

Feedback from the initial IMS sessions has already yielded tangible design updates. Palou told indycar.com that the driver cooling system experienced significant improvements. Unlike the current car, which relies on cooling ducts retrofitted as an afterthought around the 2020 aeroscreen, the IR-28 features large, strategically integrated ducts designed into the carbon fiber body from the outset to channel air upward.

First On-Track Traffic and Future Testing Timeline

Monday’s session also marked a developmental milestone when Palou executed the first-ever on-track pass in the IR-28. Overtaking a current car driven by Andretti Global’s Kyle Kirkwood, who was conducting a tire test alongside Team Penske driver Scott McLaughlin, happened organically while evaluating how the new machine handles turbulent air in traffic.

Alexander Rossi is scheduled to take over testing duties on Tuesday at the Florida circuit. Both drivers continue working through an extensive checklist alongside Dallara and INDYCAR officials. While evaluating the chassis, Palou expressed optimism regarding the car’s aesthetic, perceived safety, and capacity for closer racing across road courses, street circuits, and ovals.

Teams continue using the extensive telemetry database gathered from current-generation cars at Sebring to benchmark the IR-28's performance metrics. With testing ongoing well ahead of the 2028 introduction, engineers retain sufficient runway to resolve component failures or aerodynamic adjustments before competition starts.