‘Another piece of the puzzle’ – Carlos Sainz carries out Williams FW48 seat fit

Carlos Sainz has carried out a seat fit in the Williams FW48 car ahead of the team’s belated start to F1 2026 pre-season testing.

It comes after James Vowles, the Williams team principal, confirmed on Wednesday that the team will join the action at the second test in Bahrain next month.

Carlos Sainz carries out Williams FW48 seat fit

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Williams is the only team absent from this week’s collective shakedown in Barcelona due what the team described as “delays in the FW48 programme.”

Speaking to PlanetF1.com and other select media on Wednesday, Vowles admitted the decision to miss Barcelona testing was “incredibly painful” and conceded that “it clearly wasn’t our plan.”

He went on to insist that the delays came “as the result of our determination to push the limits of performance under the new regulations” for 2026.

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Vowles added that he is “confident it [the decision to miss Barcelona] was the right one” to prepare the team for the final two tests in Bahrain next month and the season-opening Australian Grand Prix on March 8.

Following Vowles’ comments, Williams has posted images to social media of Sainz carrying out a seat fit in the team’s 2026 car in the factory on Thursday.

The photographs are accompanied by the caption: “Another piece of the puzzle complete.”

For context, Sainz’s 2026 seat fit comes almost two months after Valtteri Bottas completed his seat fit with the brand-new Cadillac team, which posted images of the milestone on December 8 2025 – 24 hours after the final race of last season in Abu Dhabi.

Mercedes, meanwhile, released footage of Kimi Antonelli carrying out his seat fit in the new W17 car on January 10.

After a muted start, Sainz enjoyed a fine first season with Williams in the F1 2025 season following his high-profile move from Ferrari.

The Spaniard, 31, came away with two podium finishes after finishing third in Azerbaijan and Qatar, also matching the result in the United States Grand Prix sprint race.

Williams, a long-term Mercedes engine customer, has targeted the F1 2026 season for some time due to the major rule changes, which have seen the introduction of 50 per cent electrification, fully sustainable fuels and active aerodynamics.

Vowles told PlanetF1.com and other select media on Wednesday that Williams could have made the test in Barcelona, but risked being short on spare parts for the start of the season.

Williams previously fielded a single car at the third round of the 2024 season in Australia – a race won by Sainz in his final year with Ferrari – due to a lack of a spare chassis.

Vowles explained: “In terms of Barcelona, we could have made Barcelona testing – simple as that.

“We could have made it, but in doing so I would have to turn upside down the impact on spares, components and updates across Bahrain, Melbourne and beyond.

“The evaluation of it was that for running in a cold, damp Barcelona, against doing a VTT [virtual test track] test, against the spare situation, and frankly, there was zero points for running in a shakedown test, we made the decision.

“I stand by it that the right thing to do is to make sure we’re turning up in Bahrain correctly prepared and prepared in Melbourne as well.”

Additional reporting by Thomas Maher

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