Red Bull boss Christian Horner has confirmed that his outfit did hold talks with Volkswagen about a future partnership in Formula 1.
While his team continues to search for a competitive power unit deal that will guarantee its future in F1, Horner said on Friday that VW had been a serious option longer term.
However, with the German car manufacturer engulfed in the controversy over emissions testing, Horner says the plan has now gone out of the window.
But, he also intriguingly suggested that certain 'promises' had been made to his outfit by other manufacturers regarding future engine deals.
"Of course it is publicly known that there have been discussions with the VW group, but obviously with their current issues, F1 is the last thing on their mind," he said.
"There were other discussions, that will become apparent no doubt in the future as well, and other promises that were made.
"There is an awful lot of speculation and conjecture at the moment, but once everything is finalised everything will become extremely clear."
It is unclear who Horner was speaking about in relation to certain 'promises' that were made, but it is most likely to refer to Mercedes, which Red Bull believed was ready to supply engines before it elected to veto the idea.
No deal yet
Red Bull's engine plans for 2016 are still not confirmed, and it has emerged in Austin that Honda could now be a possibility for the team as a short-term solution.
Ferrari and Mercedes do not want to supply power units, and although a deal with Renault remains possible, it is understood that neither party is particularly eager for their relationship to continue.
Horner said that there were numerous options still available, and that nothing could be ruled out, although suggested the Renault situation would become clearer imminently.
"Obviously discussions have been going on with Renault to understand what their plans are for next year, but until they commit to be in F1 or not, it is difficult at this stage to take it any further.
"We have an agreement with Renault that runs until the end of next year, about which there has been a lot of speculation. I am sure there will be confirmation of that agreement in the coming days."
Stay in F1
The fact that Red Bull is considering Renault or Honda for engines shows that Horner is not resigned to the outfit quitting F1.
"For me it is not an option," said Horner about the team not being in F1. "We have to find a solution and I am working very hard to ensure that the team is on the grid and competitive for next year and beyond."
When asked if it was still an option for Dietrich Mateschitz, Horner said: "Of course it is, it is his team at the end of the day.
"But he recognises the commitment and skill and determination within the team and he wants to find a solution going forward.
"He is committed to helping that behind the scenes and is involved in numerous discussions to try to facilitate that."