One unusual detail caught the attention of Formula 1 fans during Friday and Saturday qualifying at Silverstone: both Mercedes drivers completely lifted off the throttle just a few metres before crossing the finish line. It looked counterintuitive, as drivers normally keep the accelerator fully open until the very last moment to extract every possible thousandth of a second.
As strange as it may seem, there are situations where lifting off the throttle before the finish line can actually provide an advantage by exploiting specific details within the Formula 1 regulations. After qualifying, Andrea Kimi Antonelli described the technique as unnatural to drive, but also explained that modern power unit regulations reward teams that find the most efficient ways to maximize the electrical system.
“It wasn’t easy. In Q3 I also had to lift, and with these power units it’s always a bit complicated because sometimes you have to drive in a way that doesn’t feel completely natural. Sometimes you have to get back on the throttle later, so you carry more speed through the fast corners and only accelerate afterwards. You might lose a little on corner exit, but you gain it back because by delaying throttle application you have more electrical energy available further down the straight,” Antonelli explained.
“That’s why the simulator work was so important, so these things become automatic. At first you even ask yourself why you should lift at all. It’s complicated, but thanks to the preparation we did together with the team, it has almost become second nature.”
The principle described by the Mercedes driver applies to every team. Ferrari, for example, had already instructed Lewis Hamilton from Friday onwards to carry more speed into and through the Becketts complex, allowing him to delay throttle application before the Hangar Straight. Although this slightly compromises corner exit, the benefit is that the MGU-K can remain active for longer on the straight, where the performance gain is considerably greater.
Mercedes found a different way to exploit the regulations
Mercedes’ solution, however, is based on a slightly different principle that perfectly illustrates just how complex the current Formula 1 technical regulations have become.
Whenever the MGU-K stops delivering power, FIA regulations require teams to follow a progressive power reduction curve for safety reasons.
Why the power reduction ramp exists
Imagine a car travelling at full speed down a straight. If the electrical system suddenly dropped from 350 kW to zero instantly, the driver would immediately lose more than 500 horsepower, creating a potentially dangerous difference in speed. To avoid this, particularly on high-speed circuits like Silverstone, the regulations require power to decrease in a linear fashion, limiting the reduction to a maximum of 50 kW per second.
The rule was primarily introduced for safety during races, where sudden speed differences between cars could become hazardous. Qualifying, however, presents a completely different challenge. Teams want to use every last joule of electrical energy over a single lap.
Earlier this season, Mercedes and Red Bull found a way to bypass the rule by activating an emergency procedure that completely switched off the MGU-K. Because the system could remain disabled for around a minute, the FIA judged the practice to be a potential safety risk and banned its use in qualifying for performance purposes.
Mercedes has now found an ingenious way to reproduce a very similar effect while remaining fully within the regulations. The solution relies on a careful interpretation of the rulebook that allows the MGU-K to reduce its output more quickly under very specific circumstances, even if some may argue that the regulation was never intended for this type of application.
The lift before the finish line
The key question Mercedes engineers asked themselves was simple: under what conditions does the mandatory power reduction ramp no longer apply?
The regulations list several exceptions where the MGU-K is allowed to reduce power much more rapidly. One of those occurs when the driver completely lifts off the throttle. At that point, the internal combustion engine is no longer requesting power and instead begins to decelerate, meaning the MGU-K must respond immediately.
Imagine a driver suddenly coming off the throttle. If the electric motor continued to deliver full power, the requested deceleration would never happen. Mercedes cleverly exploited this situation by programming the control electronics so that, using the car’s position on the circuit determined through travelled distance, the system would ignore the normal power reduction ramp and instead keep the MGU-K delivering maximum output for longer.
The driver then simply had to lift off the throttle a few metres before the finish line. Just before the battery became depleted, the MGU-K could instantly cut its output instead of following the gradual reduction curve, while still remaining fully compliant with the regulations. It is an extremely clever solution, even if it feels highly unnatural from the driver’s perspective.
Silverstone is particularly well suited to this strategy for two reasons. First, the distance between the final chicane and the finish line is relatively short, making it easier to perform the lift precisely at the correct point. Secondly, both through and on the exit of the final chicane, the FIA regulations provide several opportunities to reduce power rapidly and preserve energy for the final acceleration zone.
Such a system naturally requires extremely precise calibration. Both the driver and the software must work in perfect harmony, with the control unit knowing exactly where the car is on the circuit and precisely when the battery is about to be depleted, allowing the MGU-K to continue delivering maximum power until the very last possible moment.
Andrea Stella admits McLaren was surprised
Speaking after Saturday’s qualifying session, McLaren team principal Andrea Stella admitted Mercedes’ solution had caught his team off guard.
“Once we saw it yesterday during Sprint Qualifying, when Antonelli used it, we were a little surprised because it wasn’t something we had discussed. I’m not even sure it’s available to us because it probably requires some additional elements, let’s put it that way, to fully exploit the power unit,” Stella explained.
McLaren has not yet introduced its latest reliability-related power unit update because of its engine usage cycle.
“As I’ve already said, there are certainly technical discussions taking place with HPP to make sure we’re exploiting everything this power unit has to offer, because it’s an extraordinary piece of technology. There’s a lot of performance available, and much of it comes down to the fine details of how it’s used. We’re now waiting to understand whether we can update our specification and whether that could help in terms of how we use it. It should only be a reliability update, so I don’t think that’s really the key issue.”
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