In the wake of Formula 1's 2025 pre-season testing at Bahrain, suggestions were abound that a handful of teams suspected that their rivals had employed some form of "mini-DRS" on the straights.
Video footage emerged on social media of Mercedes' rear wing appearing to tilt back at high speed. Other footage shared appeared to point at McLaren's outboard slot gap expanding at high speed before closing up in the braking zone. Ferrari has also been suspected of using "mini-DRS" trickery in Bahrain.
Suspicions aside, evidence is - at best - circumstantial. In the case of the McLaren rear wing, it would be incredibly difficult to spot the purported mini-DRS unless one was being told what to look for.
Mercedes' tilting wing appears to be a little bit more visible and fits into the flexi-wing mould more than the mechanisms termed as mini-DRS, as the trailing edge leans back on the straight.
Whether teams are suspicious about their rivals' new rear wings or not is moot at this stage, as the new regulations governing more stringent flex tests do not come into force until the Australian Grand Prix.
What the rules say
Firstly, it's important to contextualise pre-season testing. It is run to effectively the same regulations as free practice at F1 weekends, in that the cars must be fully homologated - but are not necessarily subject to the legality requirements detailed in the regulations for qualifying and the race.
For example, running with aero rakes is permissible; these could never be run in the official grand prix sessions outside of practice. There is no scrutineering process at testing.
As such, the teams could theoretically run aero components that are in no way legal during sessions subject to the full gamut of technical regulations - as long as the crash structures have been approved in the FIA's homologation testing.
With the limited remit of testing it would be folly to do so, although one could foresee an eventuality where an off-season rules change might require a team to conduct A/B testing to assess the difference between specifications.
Then there's the new regulations governing flex tests and slot gap size. The rear wing mainplane may not flex more than 6mm in the direction of the load applied, and the upper flap cannot flex more than 7mm when load is applied horizontally. The trailing edge is even more strictly governed, with a maximum of 3mm of flex.
The minimum gap between the front and rear wing has also been changed. This has shrunk from 10-15mm to 9.4-13mm and, with DRS open, the upper boundary remains at 85mm. The regulations state there must only be two defined 'modes' - a DRS closed mode satisfying a defined value within that 9.4-13mm gap size, and the 85mm maximum slot size for DRS.
Article 3.10.10 in the 2025 technical regulations states that: "Except in the event of a DRS failure or the transitioning from one position into the other the DRS bodywork can have only 2 positions, such that the DRS Bodywork position must be the same before and after each state of deployment. The transition time between the 2 positions must be less than 400ms."
Furthermore, the new rules (with an addendum at Article 3.15.17) states that the distance between the rear wing profiles and the non-DRS affected tip section on the upper element "must not vary more than 2mm" when two downward 750N forces are applied simultaneously to the rear wing profiles' most forward section.
Hence, it's much more difficult to apply that mini-DRS logic, although not impossible.
What does it mean for the Australian Grand Prix?
At the moment, this all means nothing - teams are free to do what they want in testing, and everything stated at the moment is conjecture. That doesn't mean that it won't develop into anything further, but rival teams' complaints are at this stage the equivalent of micturating into a hurricane.
The outcome of flex tests in Australia will ultimately define what happens next. Should all the wings pass, then there's not much more that the FIA can do to govern the wings - it has created the boundaries, and the conditions under which those boundaries are monitored.
If a team still manages to induce a "mini-DRS" effect that fits those boundaries, then they should be lauded. Of course, the rival teams won't do that - they'll be knocking on the stewards' door with a dossier of materials with the hope that these are incriminating enough. And that's fine too, that's their job.
Either way, any conclusions about the "mini-DRS" concept or the further pursuit of flexi-wings will remain a storm in a teacup until the season actually begins. And, of course, we look forward to having the same conversation next season...
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