Mercedes has identified a software fault in its new power‑unit management that contributed to George Russell suffering a drop in top speed relative to team‑mate Kimi Antonelli, the squad’s deputy technical director said as it searches for answers ahead of the Hungarian Grand Prix.
Software, used units and race consequences
Simone Resta told media the team uncovered a bug in the power‑unit software that led to an imbalance in how energy was distributed. The fault was present across all cars, he said, but manifested more severely on Russell’s machine — a situation compounded by the Briton running an older, more worn unit.
“We found a bug in our software, and we had to react to it,” Resta said. “There was already something there at Silverstone, but the issue was more evident at Spa, which is one of the tracks with the highest lap time for power delta.”
Resta emphasised the complexity of the new power‑unit regulations and acknowledged that Mercedes, along with its engine partners at HPP, is still in a steep learning phase after only around 10 races under the current rules. He suggested the confluence of software behaviour and differing states of power‑unit wear explained the divergent performance between Mercedes’ drivers.
How it affected races
The imbalance in energy deployment had on‑track consequences, the deputy technical director said. It was visible at Silverstone and became more pronounced at Spa‑Francorchamps — a circuit where raw power and top‑speed differentials play a larger role — and was a factor heading into Budapest.
The software issue also indirectly contributed to Russell’s early exit from the Belgian Grand Prix. On the Kemmel Straight he lost ground to rivals, was engulfed in traffic and was subsequently spun into the gravel by former team‑mate Lewis Hamilton, ending his race on the opening lap.
- Root cause: a bug in the power‑unit software that altered energy distribution.
- Driver impact: Russell’s older power unit amplified the problem; Antonelli benefited from a fresher unit.
- Track sensitivity: issue more evident at Spa, detectable earlier at Silverstone.
| Track | Visibility of issue | Notes |
|---|---|---|
| Silverstone | Present | Initial signs detected |
| Spa‑Francorchamps | More evident | High power‑delta circuit amplified the effect |
| Budapest | Expected resolved | Team says they have “nailed it” ahead of the race |
Team dynamics and next steps
Resta was at pains to note the software package is common to both cars, and that the issue did not single out Antonelli’s chassis. Rather, Antonelli’s advantage came partly from running a fresher power‑unit, which by definition delivers a marginal performance edge over a more used unit.
“So, there’s a bit of everything,” Resta said, framing the problem as the sum of software behaviour, the different life cycles of the power units and the divergence in each driver’s programme. He added that Mercedes and HPP have been working to correct the code and that they believe they have understood the issue in time for Budapest.
For Mercedes, the discovery underlines the fragility of performance margins under the sport’s latest technical regulations. With closer scrutiny from rivals and the championship tightening as the season progresses, ironing out software and energy‑management quirks is likely to be a priority.
Russell’s misfortune also highlights how technical irregularities can cascade into race incidents that have sporting consequences beyond lap times, stretching from qualifying and straight‑line speed to incidents in wheel‑to‑wheel combat.
As teams continue to adapt to the new power‑unit framework, Mercedes will be monitoring unit allocations, software patches and any knock‑on effects on strategy and reliability. The coming rounds will show whether the fixes and fresher hardware on Russell’s car translate into restored competitiveness.
