Team figures recently played down speculation Red Bull could dump struggling Renault and switch to another engine supplier, saying it is "100 per cent" certain the final Adrian Newey-penned RB11 will have a French-made V6.
But billionaire Mateschitz seems to have a different view.
When asked about world champion Sebastian Vettel's recent derogatory description of the current Renault-powered Red Bull, Mateschitz said on Friday: "When he said 'cucumber', he was talking about the engine or the entire power unit of our car.
"He has a point," said the low-profile Austrian.
"The car itself is excellent, and also strategically no mistakes are being made. Sebastian knows that too."
Recently, Dr Helmut Marko said Red Bull's upper management would sit down this weekend in Austria and make a 'final report' about the team's progress in the wake of Renault's disastrous early form in 2014 and subsequent recovery.
Mateschitz confirmed on Friday: "There will be this final report.
"And then we will decide if there is still potential development in the existing engine, or whether we need to consider a new development in order to reach Mercedes' standard."
Previously, however, Red Bull officials have played down the possibility of a Renault split, as F1's only other engine suppliers are arch rivals Mercedes and Ferrari.
But there have been rumours linking Red Bull with Volkswagen, or a potential move to build a bespoke 'Red Bull' turbo engine -- perhaps in the outfit's forthcoming Newey-led 'Advanced Technology Centre'.
When told there are no real alternatives to Renault, Mateschitz insisted: "There are always alternatives, of course.
"But I don't see Red Bull using a customer Mercedes engine. Because Mercedes wants to be world champion not just this year but also in the next few years."
Finally, Mateschitz gave his tip for the winner of the football world cup, and the F1 world championship.
"When Messi is on top form, then it's Argentina," he said. "And in formula one, Lewis Hamilton."