Formula 1 is facing fresh 'mini-DRS' intrigue ahead of the new season, with onboard footage from Bahrain testing prompting suspicions that some teams are again playing around with this concept.
With teams having revealed their new cars in public for the first time in Bahrain this week, engineers have been keeping a close eye on the designs their opposition have unleashed.
And rear-facing onboard camera footage from the test has already triggered discussions in the paddock about whether some designs could be pushing the boundaries of what is allowed with rear wing flexing - despite efforts by the FIA to drive out the so-called 'mini-DRS' effect for 2025.
One team principal said: "Looking at the videos we have seen, some of the rear wings out there appear to be quite flexible. It is something we are keeping a very close eye on."
Paddock sources suggest there are two key behaviour characteristics that have emerged: one of the entire rear wing structure rotating back, and another of some squads continuing to play around with opening up the slot gap when the car is at speed on the straight.
Last year, it was McLaren's antics in this latter area - opening up the slot gap to help reduce drag and boost top speed - that helped earn its concept the 'mini-DRS' nickname.
Speaking on the final day of pre-season testing in Bahrain, Red Bull technical director Pierre Wache told The Race that he had no doubts some squads again appeared to be exploiting the mini-DRS idea.
"It is still going on," he said. "I think Ferrari and McLaren are doing the mini-DRS stuff still."
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With teams' designs not checked strictly for legality compliance during testing, there is no suggestion of teams lodging any formal complaint about the rear wing designs at the moment.
However, the situation means it is likely that the behaviour of the wings will be closely scrutinised by teams in the days before the first race of the season in the Australian Grand Prix.
If teams see similar antics there, then they could choose to take matters further if they feel the FIA should take a closer look.
Asked if he anticipated the matter becoming a talking point over the early stages of the season, Wache said: "It will be. It is quite visible."
Last season, McLaren found itself at the centre of intrigue over its rear wing design after its mini-DRS helped Oscar Piastri win the Azerbaijan Grand Prix by holding off Charles Leclerc's Ferrari on the straights.
The concept triggered complaints to the FIA from rival teams and, following discussions between McLaren and the governing body, modifications were made to the wing for subsequent races.
As part of an effort to draw a line under other teams pursuing similar rear wing tricks, tweaks were made to the regulations for the start of this season.
Revised regulations stipulated that the slot gap width was reduced from a 10-15mm minimum allowance to 9.4-13mm - with the upper boundary still remaining at 85mm when DRS was open.
Of more significance, however, was a clear regulation that stated the DRS bodywork position could now only either be in the open or closed state - so cannot be flexed to be in states where it moves around.
Article 30.10.10 of the F1 technical regulations states: "Except in the event of a DRS failure or the transitioning from one position into the other the DRS bodywork can have only two positions, such that the DRS bodywork position must be the same before and after each state of deployment. The transition time between the two positions must be less than 400ms."
Further revisions have also been made to force teams to stiffen up the rear wing mainplane.
A new Article 3.15.17 states: “The distance between the two sections of RV-RW-PROFILES and RV-RW-TIP inboard of Y=525, must not vary more than 2mm when two loads of [0,0, -750]N each, are applied simultaneously to the rear wing profile forward most section only."
