Multiple checks by the FIA, including a more detailed inspection after Formula 1's Miami Grand Prix on Sunday night, have given McLaren's under-the-spotlight rear brake design the all-clear as a clever but legal concept.
McLaren's advantage in the way it can manage rear tyre temperatures better than any other team has prompted plenty of intrigue about what the squad is up to.
Rival teams have been trying to work out exactly where its advantage is coming from, with the focus having narrowed down to the way that McLaren is cooling the outer surface of its rear brake drum - which then helps in stopping the wheel rim and tyre that sits over it getting too hot.
The inability of rival teams to fully understand what McLaren is doing has prompted some to question whether it may be operating in a grey area of the regulations.
It is understood that thermal images Red Bull had obtained from an outside party, which revealed some intriguing cold spots on the McLaren rear brake drums, had been shown to the FIA as part of an ongoing dialogue on the matter.
But despite repeated chatter on the matter, and even some suggestions that McLaren had been forced to change its design, the squad insisted that there was nothing untoward happening.
McLaren CEO Zak Brown, who teased rival Red Bull with a 'tire water' bottle stunt in Miami, was adamant last weekend that his team had not had to alter anything.
Asked by The Race in Miami if the FIA had asked the team to change anything on its car regarding tyre or brake temperature management, Brown said: "No. Nothing."
FIA checks
The Race understands that following questions posed by McLaren's rivals, the FIA has duly taken a closer look at the McLaren brake design at recent races to find out for itself what is going on.
Sources have suggested that after McLaren secured a 1-2 in the Miami GP, a more thorough inspection of the braking system, ducts and drums was conducted by FIA personnel on Sunday night in a bid to finally put the matter to bed.
There has been no formal documentation about the results of that inspection yet, and if this was part of the extra "extensive physical inspections" that the FIA does on a selected car after each race, then that will not be officially confirmed until the eve of the Emilia Romagna GP later this month.
However, with there being no notification to the team or officials on Sunday night about any problems having been found, then it is almost certain that any forthcoming note will give it the all clear.
And that would mean, as was the case in previous inspections the FIA has conducted, McLaren's design fully complies with the regulations - and that it is simply a clever design.
Targeted gains
After McLaren's dominant result in Miami, with Oscar Piastri and Lando Norris in a class of their own as George Russell's third-placed Mercedes came home 37 seconds adrift, team boss Andrea Stella made some pointed references to the job his team had done in working on tyre temperature management over the winter.
"I just want to take the opportunity to praise the work that has been done by the engineers at McLaren," he said.
"This is in terms of identifying these factors, and designing these factors in a way that is practical, to actually cash in this kind of benefit.
"And then master one of the matters that still in F1 looks like it's a little bit of a black art, which is dealing with tyres. So very proud of the team."
Stella also explained how McLaren had made some specific efforts over the winter to deliver improvements in tyre management.
"It's a result of some very targeted engineering work," he added. "If you had asked me before the season, I would say like, we have invested in improving the interaction with the tyres.
"But I wouldn't have said that the extent would have been the one that we see in this kind of race."
Mercedes is one of the teams that does not have an answer as to how McLaren is so much better with its tyre temperature management.
But team boss Toto Wolff was emphatic on Sunday night that McLaren's advantage was down to it simply doing a better job than anybody else - rather than operating outside of the regulations.
"The team around Zak, Andrea, Rob Marshall, these are good people with integrity," said Wolff.
"If in the past we may say, 'Let's look whether there's something borderline', I have no doubt that these guys stay within the rules.
"It's just really a good development, that car. They've understood how to manage the tyre much better than everyone else. In my opinion, it's totally legit.
"From a team management point of view, when someone is doing a better job than you, we should not look at that and say, 'They're cheating' because that's not the right attitude. We just need to come better and eventually not be 30-35 seconds behind over 55 laps."
While Red Bull has paid close attention to what McLaren is doing, team principal Christian Horner didn't feel there was anything illegal on McLaren's car.
Asked on Sunday if the team had ever considered protesting McLaren, as it did with George Russell's car after the Miami race, Horner said: "We're not reporting or suggesting there's anything illegal on the car, we felt George Russell has done something which is in breach of the regs..."
He added: "McLaren is the standout car. They have the kind of advantage we saw a couple of years ago.
"They're obviously doing a very good job in managing temperatures and particularly, if you look at the end of the medium stint, that was probably where they were the most competitive. That's what we need to focus on.
"I think we had brake issues that have compounded the problem in the race, but that's what we need to understand moving forward."
