Toto Wolff says there is "zero chance" Formula 1 will hit reverse gear on the all-new regulations for 2026.
In Austria, both Red Bull team boss Christian Horner and Max Verstappen made public their concerns about the new rules that will dramatically increase the electric elements of the power units.
Horner says that could add another 30kg to the already-hefty F1 cars.
"You're looking at sportscar type of weight through the cooling that's going to be required," he said, as Red Bull works on its own engine project in collaboration with Ford for 2026 and beyond.
"We need to ensure we're not creating a technical Frankenstein which will require the chassis to compensate to such a degree. We're worried there will be no tow effect, no DRS because effectively you're running at that all the time. The combustion engine just a generator to recharge a battery.
"I think that could easily be addressed with just tuning the ratio between combustion and electrical power," Horner added.
He even warned that drivers may be so desperate to recharge batteries that they will be "downshifting on the straights".
"I know the FIA are taking it very seriously. They're looking at it very closely as the simulations become more advanced."
Indeed, it is believed that at recent F1 Commission meetings, wider concerns have been raised about the 2026 batteries' ability to keep up with the rules' lofty aims.
"I've been talking about that as well with the team," world champion Verstappen agreed. "I've seen the data already on the simulator as well.
"To me, it looks pretty terrible," said the Dutchman. "It looks like it's going to be like whoever has the strongest engine will have a big benefit."
Verstappen is also worried that the need for active aerodynamics to compensate for the loss of drag will make the cars "awkward" to drive.
"I prefer to control it myself," he insisted. "If the system has to control that for you, I don't think that's the right way forward.
"We have to seriously look at this because '26 is not that far away. And it's not something I'm very excited about at the moment."
Mercedes boss Toto Wolff, however, said he will stridently oppose any moves to tinker too seriously with the 2026 rules.
"All the manufacturers were involved in the process of developing these regulations," he said. "A compromise was reached which means Audi finally joins our sport and Honda stays.
"Do our chassis designers say 'How are we going to do this?' Yes they do," Wolff admitted. "But there is zero chance that these rules will change or be delayed.
"The world needs to show innovation related to ecology and we are looking forward to it."
What Wolff does concede, however, is that F1 must work not to add too much to the hefty weight and size of the cars. But he says Horner's position is basically "alarmism".
"I suppose he is worried that his engine program is not working and maybe he wants to kill the regulations because of that. You always have to wonder about the motivation behind such statements," said the Austrian.
