Red Bull's highly anticipated works deal with Porsche for 2026 and beyond is at risk of falling through.
Auto Motor und Sport reports that Formula 1's currently dominant team is nervous about the influence that the Volkswagen-owned German sports car maker would have in the event of a rumoured 50 percent buyout.
Red Bull wanted to make the deal public recently at the Austrian GP, and since then the long delayed 2026 engine regulations were set in stone by the FIA.
However, Dr Helmut Marko admits the delayed Red Bull-Porsche deal is not ready to be finalised because it is a "complex sitation".
Team boss Christian Horner added: "There are still many details to be clarified. Porsche is welcome, but the matter is not that simple.
"I hope that the negotiations will come to a good end."
Following Honda's decision to officially exit F1 at the end of last year, Red Bull set up its own engine subsidiary - Red Bull Powertrains - which already has 300 staff.
"The alternative would have been a customer engine with Ferrari or Renault," Horner said.
Now, however, Honda is showing signs of wanting to re-join the Formula 1 party - giving Red Bull both a plan A, plan B and even a potential plan C for 2026 and beyond.
"We can now build our own engine on our own," Marko insisted. "Then we would be the only team next to Ferrari to develop the car and engine under one roof."
The deadline for a Red Bull-Porsche deal is now thought to be mid-December, so that Porsche can enjoy the 100-day period of no strategic decisions before a looming $85 billion IPO.
