Antonelli Was So Fast Mercedes Changed His Engine to Check His Pace
James Vowles has revealed how Andrea Kimi Antonelli’s extraordinary Formula 4 performances prompted Mercedes to conduct an unusual experiment, swapping his engine to establish whether his dominance came from the driver or the machinery.
Andrea Kimi Antonelli’s exceptional talent was evident long before his arrival in Formula 1. But his early performances were so impressive that Mercedes felt compelled to investigate whether a technical advantage was contributing to his remarkable pace.
James Vowles, now Williams team principal and formerly a key figure in Mercedes’ driver development programme, has revealed that the German manufacturer deliberately changed Antonelli’s engine during his 2022 Formula 4 campaign to assess the true extent of his ability.
The experiment only strengthened Mercedes’ belief that it had identified an exceptional talent.
A Formula 4 performance that raised questions
Antonelli had already established an impressive reputation in karting, but Mercedes knew that success in the discipline did not necessarily guarantee an equally successful transition to single-seater racing.
His first full season in Italian Formula 4 in 2022 quickly removed many of those doubts.
Speaking to Formula 1’s official channel, Vowles recalled how Antonelli immediately demonstrated a level of performance rarely seen among drivers making their first steps in single-seaters.
“He was fantastic in karting, but you never really know how karting performance will translate into single-seaters,” Vowles explained.
“Yet in his first year in single-seaters, he wasn’t just winning. He was two and a half tenths ahead of everyone else.”
“That doesn’t happen in Formula 4. Everyone explained it by saying he had done an enormous amount of testing, but that wasn’t the case. He had only completed six days of testing.”
Such a substantial advantage raised an important question within Mercedes.
Was Antonelli genuinely that much faster than his competitors, or was he benefiting from an exceptionally well-prepared car?
At the time, Vowles was still working alongside Mercedes team principal Toto Wolff and junior programme director Gwen Lagrue.
Together, they decided to investigate.
“We were also asking ourselves a question, and it was a discussion between Toto, Gwen and me: was our judgement being biased simply because we had a very good chassis, perfectly assembled, and a very good engine operating at its maximum?”
Mercedes deliberately swapped Antonelli’s engine
Rather than relying solely on performance data, Mercedes decided to conduct a practical test.
During the Formula 4 season, the team deliberately replaced Antonelli’s engine to establish whether the original power unit had been responsible for part of his advantage.
The outcome was decisive.
“At one point during the season, we removed the engine and installed another one,” Vowles revealed.
“We deliberately made that change, and he kept winning. Same advantage.”
For Vowles, the experiment provided compelling evidence that Antonelli’s exceptional pace was primarily down to his driving ability.
“From that moment onwards, if you had asked me, I would have told you he was really, really good.”
“I have rarely seen such a successful transition into single-seaters. And he continued on that trajectory throughout his junior career.”
Antonelli went on to win 13 of the 22 races in the 2022 Italian Formula 4 championship, underlining the consistency of his performances.
He maintained that momentum in 2023, securing the Formula Regional European Championship title and further convincing Mercedes that his development could be accelerated.
Mercedes took an unusual route to Formula 1
Rather than following the conventional progression through every junior category, Mercedes made the bold decision to promote Antonelli directly from Formula Regional to Formula 2.
The team also established an intensive Formula 1 preparation programme designed to accelerate his transition to the highest level of motorsport.
Vowles believes that decision was justified, even if the rapid progression created additional challenges for the young Italian.
“Mercedes made a very brave decision, and it was the right one, to move him directly into Formula 2 while running a very intensive F1 preparation programme alongside it.”
“And I think he undoubtedly suffered because his rise to Formula 1 was so rapid. He therefore spent a year trying to catch up.”
Antonelli’s debut Formula 1 season was marked by a demanding learning process, with the Mercedes youngster experiencing the difficulties that often accompany such an accelerated career path.
However, his development in 2026 has demonstrated why Mercedes was prepared to take that risk.
Vowles impressed by Antonelli’s transformation in 2026
Antonelli has emerged as a leading contender in the 2026 Formula 1 championship, displaying not only impressive outright speed but also the consistency and race management expected of an established front-runner.
His progress has impressed Vowles, despite the Williams team principal having recognised his potential several years earlier.
“Credit to Toto and the whole team. It was a brave decision, and it has paid off completely. They showed a great deal of confidence.”
“Because sometimes, when you read certain headlines in the press, everyone was wondering what they were doing. But I knew he had enormous performance potential.”
Even so, Vowles admitted that the scale of Antonelli’s improvement this season has exceeded expectations.
“I think the step he has made this year has probably surprised most people.”
“Perhaps not the team, who may have had a better understanding of his potential, but personally, I’m very impressed by the progress he has made.”
Crucially, Vowles believes Antonelli’s development extends beyond raw speed.
“Because it’s not just the speed he has gained. He’s not making mistakes either, particularly because he’s in control of the situation.”
Monza comeback highlighted Antonelli’s maturity
Vowles pointed to Antonelli’s recovery drive at the Italian Grand Prix as a particularly strong example of his growing racecraft and maturity.
The Mercedes driver fought his way forward from the back of the grid, demonstrating an ability to manage traffic and make progress without taking unnecessary risks.
“He worked his way from the back of the grid towards the front. That’s a mature race. It’s a difficult performance to deliver.”
“I remember watching it at one point and thinking: how on earth has he managed to gain eight places? Anyway, good for him.”
For Vowles, Antonelli’s performances in 2026 provide further justification for Mercedes’ decision to accelerate his development rather than follow a more traditional path.
What began as an extraordinary Formula 4 campaign, and even prompted Mercedes to question whether his machinery was giving him an advantage, has developed into one of the most notable young-driver success stories in modern Formula 1.
The engine experiment may have been unusual, but its conclusion was clear: Antonelli’s remarkable pace was no technical illusion.
