Koji Watanabe, the president of the Honda Racing Corporation, has revealed Red Bull’s decision to set up their own engine department ended any chance of them staying together for the F1 2026 season.

F1 2025 marks Honda’s last season with Red Bull as the Japanese manufacturer prepare to enter a new technical partnership with rival team Aston Martin from 2026.

Honda pinpoint Red Bull Powertrains as key factor behind F1 2026 split

Red Bull, meanwhile, will join forces with US giants Ford, who will work with the team’s newly established Powertrains division on a power unit for F1’s new rules, which will see the sport embrace 50 per cent electrification, fully sustainable fuels and active aerodynamics.

After a bruising F1 comeback with McLaren a decade ago, Honda have achieved enormous success with Red Bull over recent years having powered Max Verstappen to four consecutive World Championships since 2021.

Honda opted to officially withdraw from F1 at the end of Verstappen’s maiden title-winning season, but have continued to provide technical support to Red Bull in the years since.

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Red Bull committed to building an in-house engine department ahead of Honda’s exit in 2021 in order to ensure continuity and prevent a return to customer status in the future after a fractious relationship with previous partner Renault.

In an exclusive interview with PlanetF1.com at the end of 2024, team principal Christian Horner admitted it is “the biggest challenge” the team have faced since arriving on the grid in 2005.

Mr. Watanabe has revealed that Red Bull’s decision to set up their Powertrains division was the point of no return for Honda, whose agreement with Aston Martin was announced in May 2023.

He told Motorsport.com: “When we withdrew from Formula 1, Red Bull decided to establish its own power unit company.

“That is why there was basically no room to work together.

“We announced [we were] stopping our Formula 1 activities, but after discussions with Red Bull they wanted us to continue the activities.

“That’s why we became a kind of technical support since then. In fact, we still operate everything on the power unit side.

“From Honda’s point of view, the new F1 regulations for 2026, with the combustion engine being 50 per cent and the electrical parts being 50 per cent, are very attractive to both Honda and Honda Racing.

“The direction with the carbon-neutral fuel is very good for us as well, so that is basically why we decided to officially return to Formula 1.”

Mr. Watanabe revealed that Honda briefly considered a split program with Red Bull, which would have seen Red Bull Powertrains produce an internal combustion engine and Honda provide the electrical ancillaries.

This option is also believed to have been on the table when Red Bull were linked with a deal with Porsche, the luxury car brand owned by Volkswagen, in 2022.

However, Honda decided that such an arrangement would have been “impossible.”

Mr. Watanabe, who also revealed that Honda were approached by several teams before striking a deal with Aston Martin, added: “During our regular conversations, we discussed the option of Red Bull doing the internal combustion engine themselves and us doing the electrical parts.

“But that wouldn’t have been easy at all if they only made the ICE and we did the electrical parts, so in the end we found out that it was impossible to collaborate under these conditions.”

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Mr. Watanabe’s latest comments come after he told media including PlanetF1.com at the recent Daytona 24-hour race that Honda are “struggling” with the demands of the F1 2026 engine regulations.

He said: “We are struggling. Now we are trying our best to show the result next year.

“Everything is new. The motor is a new 355-kW, very compact one we need. Also the lightweight battery, it’s not so easy to develop. And also the small engine with the big power.

“Everything is very difficult, but we try our best.”

It is unclear if Mr. Watanabe, who was speaking in a second language, was referring specifically to Honda’s progress ahead of F1’s new era or was making a general comment on the challenges of the new rules for F1’s engine manufacturers.

Horner dismissed fears that Honda are behind their rivals on F1 2026 engine development, insisting that the Japanese manufacturer will deliver a “competitive” power unit for Aston Martin.

However, he suggested that Honda’s U-turn may have compromised the team’s preparations for F1 2026.

Horner said: “It is a big challenge.

“They disbanded their project and then restarted it again. They may well have lost a little bit of time through that.

“But they’re a very capable company and they’ve got great strength.

“I am sure they’ll have a competitive power unit come 2026.”

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