- Mercedes and Red Bull engines exploit a legal MGU-K loophole.
- Cars using these engines ground to a crawl at Suzuka, exposing flaw.
- Ferrari demands answers, and the FIA is now watching closely.
A clever engineering trick has caught the attention of the Formula 1 paddock. Teams running Mercedes and Red Bull power units have found a way to squeeze extra electric power at the end of qualifying laps, and the backlash has already reached the FIA.
The trick exploits a loophole in how the MGU-K, F1’s electric motor, can be switched off. It is clever, it is currently legal, and it is making Ferrari very uncomfortable.
How the trick works
To understand the controversy, it pays to first understand the rules. Under F1’s 2026 regulations, teams must reduce MGU-K deployment in steps: 50 kilowatts at a time, in one-second intervals.
Think of it as a slow staircase down from full power.
Mercedes and Red Bull seem to have found a trick around this, according to a report by The Race. Instead of stepping down gradually, their engines can cut from full 350kW deployment to zero in a single move, right at the end of a qualifying lap.
That means the car holds maximum electric power for slightly longer before the finish line.
The amount of energy spent stays the same. But the timing of when it is spent changes. And in qualifying, even fractions of a second could change the position significantly.
The rules allow this sudden shutdown, but only because it was designed as an emergency measure. If a problem forces an MGU-K to cut out instantly, the rulebook permits it. What teams are not supposed to do is use it deliberately for performance.
To prevent that, the regulations attach a 60-second lockout. Use the emergency shutdown, and the engine control unit blocks the MGU-K for at least a minute afterwards.
During a race, that penalty is crippling. Losing electric power for a full minute would cost multiple positions.
But at the end of a qualifying lap? The driver is already heading to the pits. The lockout covers most of the cool-down lap. The penalty barely stings.
The smoking gun: cars grinding to a halt
The trick might have stayed hidden had it not produced a very public and perhaps alarming side effect at the Japanese Grand Prix weekend.
In Friday practice at Suzuka, Williams driver Alex Albon suddenly lost almost all power and stopped on the track. Shortly after, Mercedes’ Kimi Antonelli and Red Bull’s Max Verstappen were both seen crawling through the high-speed sweeps in the opening sector during FP2, barely moving.
Antonelli had experienced the same problem earlier in Australia during FP1, but it had gone largely unnoticed then.
According to The Race, the cause is rooted in how 2026 engines behave when both turbo boost pressure and MGU-K power drop at the same time. When a driver slows sharply to let a faster car through, the engine revs fall. Turbo boost, already fading after the finish line, drops further.
Without the MGU-K to fill the gap, the engine loses nearly all power.
This is where the 2026 design comes into focus. These engines removed the MGU-H, the heat-recovery motor that previously helped spool the turbo. Without it, the turbos struggle badly at low revs.
In normal conditions, the MGU-K masks that weakness. Here, with the lockout active, it cannot. Verstappen called what happened a “glitch” to the media.
Recovery is counterintuitive. Drivers must resist the urge to stamp on the throttle and instead bring the turbo back to life with gentle pedal inputs. Most of the time, the fastest solution is simply to wait out the lockout, which by then is usually only 20 or 30 seconds from ending.
Why Ferrari is furious and what the FIA thinks
Ferrari has made no effort to hide its frustration. The Scuderia wants the FIA to explain how an emergency shutdown mechanism, designed for safety purposes, can legally become a qualifying performance tool.
The irritation runs deeper than principle. Ferrari is chasing Mercedes in 2026. The Scuderia knows it carries an engine deficit, and every advantage Mercedes extracts makes that gap harder to close.
The FIA communicated with at least Mercedes about the trick after the Suzuka incidents, according to The Race. For now, the governing body accepts the rules permit it. But the safety concerns at Suzuka have put the FIA on alert.
Multiple cars from different teams losing power at a high-speed circuit is not something it can ignore.
Mercedes, for its part, appears to have already done the maths. The team stopped using the trick for the remainder of the Japan weekend after discussions with the FIA. The internal reasoning is straightforward: the trick is not what makes Mercedes the fastest engine on the grid.
If it carries a real risk of uncontrolled shutdowns and potentially a safety incident, it is not worth it.
The door remains open, though. Teams could study the conditions that trigger the problem, train their drivers to recognise the early signs and manage the recovery, and bring the trick back at circuits where it offers a meaningful reward, specifically those with a longer run to the finish line.
For Ferrari and others who do not yet run this system, the path to replication is neither quick nor simple. Building it into their energy management without triggering the same severe power loss takes time, especially for teams that only became aware of it in Australia.
The 2026 season is still young. The gap between Mercedes and the rest of the teams is clear. And this MGU-K controversy is almost certainly not the last time the paddock will argue about where smart engineering ends and where exploitation of the rules begins.
