Software glitch sent Russell's engine into freefall before Hungarian GP lights went out

George Russell’s Hungarian Grand Prix unravelled before the lights even went out, after a Mercedes engine software fault caused his revs to spike uncontrollably on the grid in Budapest, triggering anti-stall and leaving him almost stationary as the field accelerated away.

The start issue was the second major technical blow of the weekend for Russell. On Saturday, a water leak — caused by clipping a kerb — destroyed his original power unit, forcing Mercedes to fit a replacement ahead of the race. That context made Sunday’s grid drama all the more damaging.

Initially, Mercedes’ radio communications suggested Russell may have lifted off the throttle during the launch sequence, implying driver error. The data tells a different story. Russell dropped from roughly 30% throttle to below 10% while the lights were still on, but that reduction was a reaction to the problem, not its cause.

Team principal Toto Wolff clarified the sequence after the race. “It looks like he gave about 10% throttle and the whole thing revved maximum, he went off the throttle and it popped down,” Wolff said. “I’m really not happy about too many mistakes that happened. That was the reason — and then he drove very well.” Wolff added separately that the volume of reliability and technical failures in the first half of the season is simply unacceptable.

Russell’s own account aligned precisely with the data. The British driver said he was holding the revs normally when, approximately four seconds before the lights went out, the engine began surging beyond its threshold. His throttle modulation was an attempt to bring the revs back under control — the consequence of a software glitch, not a lapse in concentration.

The Budapest weekend served as a microcosm of Russell’s frustrating first half of the season. He acknowledged after the race that even without the mechanical trouble, a top-three qualifying result would have been unrealistic. The deeper issue was the accumulation of misfortune converting a difficult weekend into something far harder to recover from.

Russell said after the race that he needs the summer break to recharge, having arrived at the mid-season pause with more regrets than rewards from 2025 so far.