In the recent Brazilian round the troubled Milton Keynes team hedged their bets, running a version of that unit in Daniel Ricciardo’s car, and the older-specification system in team mate Daniil Kvyat’s. However, as one high-level insider revealed: “The difference between the two engines we ran in Interlagos was about a tenth - in the negative direction in the case of the latest one.”
It subsequently transpired that although Renault had used 11 of their remaining 12 tokens to develop the new unit, Ricciardo used only the new version of the ICE (internal combustion engine) and that revised ERS (energy recovery system) components weren’t fitted.
This led to speculation prior to this weekend that Renault might go the whole hog on one of the RB11s as Renault managing director Cyril Abiteboul said there would be further discussion prior to a decision being taken, but on Thursday Ricciardo made it clear that would now not be the case. Both cars will thus use the older powertrains.
"We have seen it hasn't really given us anything, so back to the drawing board for Renault,” the Australian driver said. "We have to try and find some more from it but I don't regret testing it because we had to try. We had to see if there were any positives from it and if what they saw on the dyno was replicating what we felt on track. In hindsight, it didn't give us any lap time, it's was just a penalty for a little bit of knowledge."
In Brazil he was slower than Kvyat on maximum speed, leaving the team disheartened and promoting this weekend’s decision to go back to the known quantity of the older power unit with both cars.
It still seems that Red Bull’s only option for 2016, now that team owner Dietrich Mateschitz has made entries for both Red Bull and sister team Toro Rosso, is to stick with Renault while longer-term plans are made. But Ricciardo made it clear there is still a huge amount of work to be done before they can truly be competitive.
"We need something better, we need to try a different path or something if we're going to continue together next year," he said. "I'm sure there are things Renault can learn from it. It's now about trying to put together things they have learned and actually give us lap time.
"Hopefully there are some conclusions to be drawn from this engine and we have only run it for two days, so hopefully there is still something in there we can extract from it. But right now it hasn't proven to be the ingredient we wanted.”
Like McLaren, equally troubled by poor performance from Honda’s powertrain, the final races seemed to be the place to try different things ahead of winter development and the start of testing for 2016, but the new engine was so disappointing the team took the call to ditch it here rather than to persist any further.
Reasons to be cheerful
It’s not all doom and gloom within Red Bull, however, as Ricciardo said again this weekend that that improvements wrought on the behaviour and predictability of the RB11 chassis have made it the equal of any rivals. That has been borne out by its performances recently on a wide variety of tracks, from Spa and Monza to Suzuka, Mexico City and Interlagos, some of which on paper should not have suited a car with a down-on-power engine.
"If we had more power, we could probably win races," Ricciardo suggested. "We didn't have the quickest car at the start of the year. The chassis had some deficiencies. But I think what the team's done has made the chassis back to pretty much what it was last year, which was as good as the Merc."
Kvyat supported his team mate’s views and admitted that 2015 has been “a very eventful year,” adding: “I think the start was quite painful but then I’m proud of how we managed to climb our way up through all the issues that we had.
“Since Monaco we probably started to follow the right path more or less, a bit technically, a bit myself. An up and down season but we scored some good points, we managed to start taking the maximum out of the package most of the weekends. Some strong races and some good points, but obviously we are always looking for more.
“The highlight I think was the podium [in Hungary], even though I wouldn’t say it was the best race. We had a couple of really strong races, I would say even the last couple I was quite pleased about them. In Mexico and Brazil I think we were taking the absolute maximum.”
Red Bull will finish fourth in the 2015 constructors' standings, regardless of results in Abu Dhabi.