The development of the NTT INDYCAR SERIES’ next-generation IR-28 car moved this week to the bumps and bruises of Sebring International Raceway from earlier testing on the silky-smooth surface of Indianapolis Motor Speedway.

Alexander Rossi, who drives full time for Chevrolet-powered ECR, took over testing duties Tuesday at the historic Florida circuit. The 2016 Indianapolis 500 winner continued the evaluation of the car that will debut at the start of the 2028 NTT INDYCAR SERIES season.

The Sebring test marks the first opportunity to evaluate the IR-28 away from Indianapolis, following initial sessions on the 2.439-mile, 14-turn road course and 2.5-mile oval in August and September. Five-time and reigning series champion Alex Palou completed 43 laps Monday on Sebring’s outer loop, putting the new car through its paces on a circuit renowned for its punishing surface and demanding mix of asphalt and concrete.

Palou, a Honda-powered driver for Chip Ganassi Racing, and Rossi also were chosen to handle testing duties at both IMS configurations.

The two-day Sebring test session represents another important step in the series’ extensive development program, with the IR-28 facing the kind of conditions designed to expose weaknesses long before the car reaches competition.

“It’s a new car for me at Sebring,” Rossi said. “Coming back here and being part of the next generation of INDYCAR’s future is a huge honor. It’s an exciting time in this sport. This car, in so many ways, is a pretty big upgrade from what we have.”

Sebring is a regular testing destination for INDYCAR SERIES teams, in large part because of its unforgiving character. Its bumps, uneven surfaces and relentless demands on vehicle components make it an ideal proving ground for a car expected to compete on road courses, ovals and temporary street circuits. With street circuits accounting for one-third of the 2026 schedule, durability and driver confidence over challenging surfaces remain important considerations in the IR-28’s development.

“What’s good about this place is it’s the poorest-quality surface that you can have in a permanent road course,” Rossi said. “It mimics a street course kind of. Because it’s a permanent road course, it gets used a lot, so it’s a higher grip level than a street course. In terms of bumps, pavement changes, difficult changes in the asphalt, that’s why everyone comes and tests here. It’s somewhat of a preview that you’re going to get in street courses.”

IR 28 at Sebring

Rossi’s test plan Tuesday focused on evaluating the car’s fundamental systems and performance, building on work completed during earlier sessions at Indianapolis. He worked alongside Dallara and INDYCAR officials.

The testing emphasis has evolved as development has progressed. Initial tests focused on confirming that the car’s systems functioned as expected. At Sebring, the priority was understanding how the package performs over an extended test and identifying issues that might emerge through more extensive running, especially on rough, bumpy surfaces.

“I don’t know that anyone is looking for anything (particular),” Rossi said. “The messaging we get is run the car as if it’s your race car. From there, we’ll see what issues, problems, surprises come out of that. I think all the test list items were really accomplished in the first two tests. Just making sure things worked as you would expect.

“This test is more of a practical application of: ‘Does it perform over a two-day test as the current car does? Does it do what it is expected to and kind of what little things could come out of that we need to address before the series produces a bunch of these?’”

Driver feedback remains central to that process, particularly when it comes to comfort and cockpit cooling. The IR-28 incorporates a more integrated cooling approach, with strategically positioned ducts designed into the initial bodywork rather than added to the existing carbon-fiber structure. Palou reported a significant improvement in cooling during Monday’s running, highlighting progress since the initial Indianapolis tests.

Rossi also experienced the benefits of those improvements at Sebring.

“First of all, visually, it’s an incredible race car to look at,” Rossi said. “It generates more grip in high-speed corners. It’s a very nice car to drive. It’s well-built and incredibly well-engineered. Cooling-wise, we made a pretty big step in this test, in particular. It’s night-and-day different in terms of comfort and drivability in the cockpit.”

Although the car’s competition debut remains more than a year away, the development schedule allows time to address concerns and validate improvements across different types of circuits before the 2028 season begins. Every lap adds another piece to that process, helping ensure the IR-28 can withstand the demands of a race weekend while delivering the performance drivers and fans expect.

“There are more things that are scheduled to come as time comes that will allow this car to race and perform even better, that will only put on a better show for the fans, which is the No. 1 priority for all of us,” Rossi said.