This year at Circuit of the Americas, NASCAR witnessed a curious phenomenon. Cars belonging to the Cup Series, the expected premier tier of the series, were slower than cars belonging to the Xfinity Series, now called the O’Reilly Auto Parts Series. Their qualifying pole timings registered almost a second of disparity – something which sent waves of depression in the Cup garage. And the reasons behind this are nuanced – in the intricate parts of every car.

Inside a NASCAR O’Reilly Car

“The body panels that make up a NASCAR Xfinity car,” champion racing mechanic and pit crew member Bozi Tatarevic wrote on X. He posted a picture of a car body belonging to the O’Reilly Auto Parts Series, dissected and taken apart for a magnified view. The notable parts include the lower front bumper covers and back extensions, which cater to superspeedway races, the rear spoiler, the rear window air deflector, the front splitter, and the grille inlet bezel, among others.

Throughout the early to mid-2000s, the NASCAR Cup Series and Xfinity Series essentially ran the same type of car. But the Xfinity Series car was usually fitted with less horsepower. In the 2010s, Cup cars exhibited around 900 hp, which made up for a vast difference. However, things gradually changed with subsequent developments, like the Cup cars’ 550 hp package in 2019-2021. But with the introduction of the Next-Gen, the two series’ cars grew further apart.

The Next-Gen and the Xfinity cars differ in many areas, like the shifting/gearbox, tires, the underbody, the chassis, etc. Despite the Next-Gen’s intentions to perform better, the opposite was evident in 2025 with lower speeds. The aerodynamic drag produced by the Next-Gen car’s underbody and rear diffuser reduces top-end speed, particularly on lengthy straightaways like those at COTA. Cup vehicles are not as quick as Xfinity cars, even with larger tires, stronger brakes, independent suspension, and world-class drivers. On a brighter note, Cup cars will advance from 670 to 740 hp for 2026.

“I know there’s talk about that much horsepower. We need that much horsepower. I think when you look at the short tracks and road courses, having too much power, I’d err to that side because there’s just no reason that the Cup cars should be the slowest thing there on the weekend. They should not be slower than ARCA,” 2014 Cup Series champion Kevin Harvick ranted after ARCA cars were faster than Cup cars at Iowa. “I think it just takes away from being a Cup driver, and in the end, the cars are so damn slow they don’t race good.”

Although the glaring defects of the Next-Gen car, NASCAR had other reasons to continue with it.

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Revealing its vested interests

Last week, the NASCAR lawsuit reached a settlement. But even as Michael Jordan and Co. shook hands with the sport’s executives, the past two weeks’ jaw-dropping evidence lingered in the background. Some of it concerned the Next-Gen car; NASCAR has invested $14 million in developing the car and owns intellectual property rights on it. What’s more, it also possesses patents on the car’s underwing, the diffuser flap on the rear wing, and the car’s outer body.

According to John Probst, a mechanical engineer who is NASCAR’s chief racing development officer, that is all the more reason for the sport to stick to the Next-Gen model. “If Coca-Cola developed a new formula, would they give it to Pepsi?” he said.

In addition to purchasing the Next Gen car and parts, Probst said a team running the entire season—36 point races and two exhibition events—would pay a big amount. That included a $134,000 entry fee to NASCAR, and the team’s driver’s license was $6,000.

Evidently, NASCAR’s Next-Gen story is more convoluted than it appears. Let’s wait and see if 2026 brings any positive change.