Ferrari's aerodynamic edge: the FTM exhaust device Mercedes tried to copy and removed

Mercedes spent a session in Madrid fitting a rear-end part borrowed from Ferrari onto the W17. Less than two days later, the part disappeared. This technical story reveals a great deal about how teams study rivals, but it also raises the key question: where does Ferrari's advantage really come from, and why could not Mercedes make the idea work? Since the return of the ground-effect era, the rear end has become the most important aerodynamic battleground. Every team wants to optimise the airflow through the diffuser and under the rear wing, because even a small gain in that area can make a big difference to stability and downforce. Ferrari entered the 2026 season with its own solution: FTM – “flick tail mode”. The device sits around the exhaust, directing hot gas upward. According to the technical description, FTM partially blocks the exhaust outlet, increases the force of the gas flow, points it upward to help the diffuser scavenge flow, and energises the underside of the rear wing. This is a way of exploiting exhaust energy, a technique seen in F1 history, especially Red Bull's blown diffuser era of 2026–2026, which was later restricted by regulation. Between 2026 and 2026, Red Bull used the blown diffuser to maintain downforce when drivers lifted off the throttle. By 2026, the idea had become even more complex with Coanda technology and the off-throttle exhaust effect, forcing the FIA to introduce new rules. FTM inherits that exhaust-to-downforce idea but works at the rear outlet area, rather than under the floor. That layout helps Ferrari avoid the main restrictions, but it remains under technical scrutiny. What makes FTM special is not the mechanism, but the time Ferrari has had it on the car. The device has been present since pre-season testing, meaning the Italian team has accumulated a large amount of data across many races and circuit types. Mercedes, by contrast, only approached the idea on one rare occasion. In Madrid, they fitted an FTM-inspired version to the W17, tried it, and then reverted to the Monza-spec exhaust configuration for the rest of the weekend. Trying and removing it quickly is not automatically a technical failure. It may reflect incompatibility between Ferrari's concept and the W17's architecture, or simply that Mercedes did not have enough time to calibrate it. But it does show that Ferrari is leading in a development direction a rival felt forced to acknowledge by copying. The difference between a part and a system is something race engineers always notice. Mercedes could copy the external shape of FTM, but it could not copy thousands of hours of operating data, chassis setup maps, or Ferrari's overall rear-end packaging. A device only works when it fits with other components. Copying a detail without the full context often leads to disappointing results, and that may be why Mercedes removed it. Looking only at the mechanism, FTM belongs to the family of exhaust-driven downforce solutions. The idea is plausible: the hot exhaust gas carries significant kinetic energy, and if directed carefully it can help the diffuser work more efficiently at its exit, where the flow is easily disturbed. The upward gas can also improve the flow around the rear-wing underside, helping the car reduce drag or maintain downforce at high speed. In theory, this is an advantage in the most sensitive area of a ground-effect car. But everything stops at the mechanism. The whole analysis provides no measured figures: no lap times, no top speed, no GPS data, and no tyre degradation comparison between the FTM version and the version without it. In other words, the “aerodynamic edge” is a plausible hypothesis, not validated performance. This is the biggest blind spot. When a team introduces a new part, it must prove its worth on track, not in a technical explanation. Ferrari may have a real effect, but it may also simply benefit from the whole car package. Mercedes trying and removing the device proves nothing certain. If the concept could not connect with the W17, dropping it early is a rational resource-management decision under the cost cap, not evidence that Mercedes is weaker than Ferrari in every respect. Having followed team testing sessions for many years, I have noticed that a part kept across many races tends to deliver repeatable value, while a part removed after a single weekend is usually the result of correlation problems or perceived risk. In Mercedes' case, the quick trial-and-revert could also be a cautious decision after reviewing internal data, and the possibility remains that they will return with a different version. One detail in the technical description made me stop. “Partially blocking the exhaust outlet to increase its force” goes against physical intuition. When you narrow an outlet, back-pressure increases, mass flow may drop, and engine performance could be affected. A device that “blocks” the exhaust may really be a flow-shaping element, turning the gas rather than genuinely throttling the pipe. Early reports may have simplified the mechanism. If FTM creates significant back-pressure, Ferrari will face durability and heat risks, especially in the turbo and ERS areas. This hidden cost is rarely mentioned in articles praising an aerodynamic advantage. There is also the regulatory side. Exhaust-driven downforce devices have historically been a grey area, and the FIA has often used Technical Directives to close them down. If FTM is judged to violate the spirit of the exhaust-outlet rules, Ferrari will be forced to make changes. A TD would level the playing field, benefiting Mercedes and every team that did not pursue the idea. F1 history is full of excellent aerodynamic details being banned after only a few races. FTM is in that risk group. The very name “mode” suggests a component that can change state, which could collide with the ban on movable aerodynamic devices if read literally. So what is the real story? For Ferrari, keeping FTM since the start of the season shows confidence from the technical team, but that confidence needs to be confirmed by independent data. For Mercedes, trying and quickly abandoning the device is a soft signal: they recognised that Ferrari had solved a problem they had not yet solved, but that does not mean they will give up. In a few months, Mercedes may return with a revised version for the W17, or focus resources in another direction. In F1, an abandoned idea is not always a wrong idea. The tactical machine is not driven by emotion; it is driven by information. In this case, information is seriously missing. Every outside assessment, including this article, can only hypothesise about how FTM creates an advantage, not how large it is. The idea of a secret device making Ferrari faster is a compelling story, but a story is not evidence. The only thing that can settle the matter is the next races. If FTM has real value, Ferrari will continue using it at circuits with different aerodynamic demands. If the device disappears or is modified, the answer will speak for itself. A transfer window – or more precisely, the technical development race – has no early winner. Ferrari is leading in a way Mercedes acknowledged by copying. But an unquantified advantage is fragile. Data from the next two race weekends will provide the answer. If the data does not come, all we have left is a plausible mechanism, a rival that tried and abandoned it, and an open question. F1 has seen many aerodynamic revolutions forgotten simply because the data was never strong enough. This time may be no exception.