Christian Horner has questioned whether Toto Wolff is as up to date with his team's 2026 engine development, as a customer team rather than a team who develop their own engines.
The pair have been going back and forth over development for Formula 1's incoming rules – with Horner questioning whether they'll be bad for the sport, with Red Bull's simulations suggesting that they'll struggle for pace.
Wolff, for his part, has been suggested that Horner is more concerned with his own team's performance than with the good of the sport as a whole.
"I'm not sure how close Toto is to his engine business, because he's a customer, he’s not involved in HPP's business formally," Horner said.
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Horner: Red Bull advances help show 2026 limitations
"The feedback that I'm getting from the business, and as you start to see the programme really coming to life and as the simulations firm up are some of the limitations. Which are inevitable.
"So I would say it's perhaps as a result of us maybe being well advanced that we're actually seeing some of the limitations.
"And I think that not for self-gain here as an engine manufacturer, just looking holistically at the whole lot, looking at the compromises that we're going to have to make on the chassis regs with fully active aero to compensate for the recovery on the engine, it still doesn't feel too late to tune that ratio.
"And it wouldn't take much. It's not like we're saying we have to rip everything up and start again. It's whether you do it on a fuel flow or the cell mass, you just need to change that ratio slightly to ensure that we get great racing."
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