Oscar Piastri hits out following energy management issues similar to those experienced by George Russell.
Throughout the Spa weekend, the Australian, like Russell at Mercedes, was unable to match his teammate's speed on the straights, and was left lost for words at the reason why.
Speaking on Saturday, post qualifying, at a time Russell was wondering if it was his driving style that was costing him pace, Andrea Stella shared his opinion.
"When you come to a circuit like this, which is inherently highly power-sensitive, these sensitivities to driving input, to how much you deploy before a certain corner, were even more visible," the Italian told reporters.
"And across team-mates, if I compare Lando and Oscar in their best lap in Q3, Oscar is losing time in the final straight and Blanchimont for reasons that have nothing to do with Oscar's driving. They are just a minor deviation in how the power unit was operated.
"I think this seems to be pretty much the same across the two Mercedes cars," he admitted. "When you overlay Antonelli and Russell, it looks like Lando and Oscar.
"We do so much work in offline simulation," he continued. "And now as a customer team, we are at race ten we are finally getting the tools to actually simulate before the event.
"I would say that most of the conversation this weekend has been about power unit and optimisation, but it's not like it only varies works team to customer team, because, like I said before, it looks like there are deviations even for the works team between one driver and the other.
"I think Piastri could have been one to two tenths faster, just if the power unit had behaved as we anticipated.
"You don't operate these power units in an open-loop way, whereby I would be able to have an offline simulation and say, 'oh, that's how the electrical power will be deployed, and it will always be identical to itself'," said Stella. "There's a large component that happens with live calculations, and the power unit kind of forward thinks, forward calculates what it has to do based on some parameters. This is why it's not so easy to understand what kind of calculations have been made as the car was going.
"This is not only for the influence it has on the straights, but also because it affects the braking points," the Italian explained, "because if you have an additional amount of energy harvesting before braking, then you are approaching the braking zone 10km/h slower and your braking point changes. This is quite difficult to master for the drivers. It's not only about getting the most out of the power unit, but also because the variations of the power unit affect your references as you approach a corner.
"(The software) definitely learns, but the variations are so small that they may happen from one lap to the other, even if you have learned from the previous laps."
"It sucks," said Piastri post-race of the anomaly that is the 2026 power unit. "I can't really say it any other way than that.
"I certainly wouldn't have been the only person," he continued. "I know George has had a lot issues with that this weekend, and maybe the last couple of weekends. And speaking to some others, it's a similar story.
"So, you know, when you've got qualifying grids decided by computers behaving or misbehaving, it's a pretty crap way of going racing.
"Here it's obviously exaggerated a lot and made worse, but yeah, when you come in from a qualifying session, you look at all the corners and go, 'I'm on par with my team-mate and yet I'm two tenths behind at the end of it'. It's not a very nice feeling."
"It's got nothing to do with you as a driver, really," added his McLaren teammate. "Sometimes it does and we're talking about being a few metres early on the button or whatever. It makes a big difference at times, but there are certain things within your control and a lot of things, way too many things, that are out of your control.
"It's a shame that there's so many things that can dictate your own pace in qualifying," he continued. "It's not down to the driver. It's just down to hoping you get lucky that the power unit does what it should do and doesn't do something silly.
"It's been costing me the whole year," said the 2025 world champion. "This is the first weekend, I think, all season that I've been competitive on the straights. It's the first time I'm probably happy. I've had the problem this whole season and this is the first race I've been the one that's like, 'oh, I'm happy in the straights for once'. It was the first time Oscar was the one a little bit on the back foot in qualifying, but it's also not up to him. It's just down to the power units doing whatever they want."
"It's all to do with just how the systems manage things," said Piastri, who doesn't believes the eventual shift to a 60/40 power split will make much difference. "The change in fuel flow and the less deployment are not going to fix those specific issues. It has to do with how the engine is calibrated, how the engine learns, it's kind of ingrained into these engines.
"Obviously it will get better as all the manufacturers understand the engines more. It's not just a problem for us or Mercedes, it's a problem with all the engines, speaking to some of the other drivers. But the fact that it's even a problem is pretty annoying for more than just myself."
Indeed, Oscar, indeed.
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