IndyCar officials discovered a seam on the rear attenuator had been filled, putting the #2 car in breach of the regulations.

Will Power’s #12 car passed inspection but was also found to have been in breach with the modification and was withdrawn from the Fast 12 by Team Penske.

Scott McLaughlin’s #3 car did not have the same modification, though he did not participate in qualifying after an enormous practice crash.

The attenuator acts as a crash structure housing the rear light and is a controlled component that cannot be modified. It’s believed the seam was filled to gain a theoretical aerodynamic advantage by reducing drag.

IndyCar technical delegate Kevin Blanch explained: “There was a body fit violation on that rear attenuator. So, as quick as this process happens, we ran them through tech, we got everybody in line, and then right near the end or prior to qualifying they decided that they would just pull out of line.”

Speaking after the #2 and #12 cars were withdrawn, Team Penske’s IndyCar program president Tim Cindric labelled the issue “arbitrary” but accepted it was a problem.

“Essentially, the #12 car had passed inspection. As the #2 car went through inspection, it was pointed out that basically the officials didn’t like what you saw on television,” Cindric explained.

“There was a blending there on the attenuator and we decided the #12 car, let’s go look at that, and the #12 car was the same way.

“There really was no reason to run the #12 car knowing that it was like the #2 car and they didn’t like the #2 car.

“I, in fact, went back and looked at the #3 car from this morning, and it didn’t have that, so it was a bit of a randomness internally that we need to sort out.

“It’s a shame we didn’t give our guys a chance to go for it.

“It’s my understanding that the #12 car actually went through inspection and the officials didn’t like the #2 car,” he added.

“When we asked if we could modify that or change that before we ran, it was understood at least initially that we might be able to do that.

“If I was one of the competitors, I’d have the same argument, that you’re only allowed to change certain things once you pass inspection. Wing angles, tyre pressures, and so forth.

“So that was outside of what you’re able to do once you go through inspection. At the end of the day, we didn’t do it right.”

It will mean that McLaughlin starts from 10th, Newgarden from 11th, and Power from 12th.

It’s in stark contrast to last year’s effort, where the team locked out the front row.

Leading McLaren driver Pato O’Ward, who qualified third, took umbrage with Team Penske for what he said was a blatant violation.

“They weren’t accidentally doing it because they had the blowtorch there in order to get it out,” said O’Ward.

The Mexican sympathised with the four drivers who had to complete the Last Chance Qualifier.

Dale Coyne Racing’s Jacob Abel was knocked out of the race while Marco Andretti (Andretti Global), Marcus Armstrong (Meyer Shank Racing), and Rinus Veekay (Dale Coyne Racing) scraped through.

O’Ward claimed the modification to the attenuator would have been present on the cars during qualifying a day earlier.

“I feel bad for Abel and everybody who did the last-chance qualifying,” said O’Ward.

“Those [Team Penske] cars weren’t in regulation. Those cars should have been in the last-chance qualifier … because they had that yesterday, I guarantee you.

“Until someone pointed it out today. If they were disqualified today, they should have been disqualified yesterday.

“It’s a shame. They don’t need to be doing that stuff. They’re a great team. They have great drivers. Why are you doing that? It makes no sense.”

It’s the second instance in a little more than a year that Team Penske has been caught in breach of the rules after the widely-documented push-to-pass scandal.