Carlos Sainz reveals Williams’ deeper 2026 problem

Carlos Sainz says inconsistent manufacturing quality, rather than the weight of Williams’ 2026 car alone, has become the team’s biggest obstacle as it tries to build a credible recovery for next season.

Speaking during the Zandvoort weekend, the Williams driver said supposedly identical parts can produce different results on track, leaving engineers unable to establish whether a setup change or upgrade has genuinely worked. The problem is particularly visible with the floor, where multiple examples built to the same specification do not behave in the same way.

“We have more floors like the one we are using, we have many of these versions, it is simply that each floor does a little bit what it wants,” Sainz said.

That variability makes development far more difficult under Formula 1’s new technical regulations. If two nominally identical components deliver different behavior, Williams cannot reliably identify the source of the FW48’s weaknesses or judge whether a new direction has improved the car. Sainz said changes can even produce the opposite effect to that expected.

“The quality and control of production of parts is one of our biggest weaknesses as a team, and generally, that is where we need to improve the most next year, I would say,” he said.

Williams missed private testing in Barcelona before arriving at pre-season testing in Bahrain with an overweight car. Its season has since left the team fighting only for positions between 15th and 17th, but Sainz has nevertheless renewed for two seasons after seeking assurances that the underlying issues could be understood and prevented from recurring.

For Sainz, solving those issues is essential before Williams can make a meaningful step with its 2027 project. “You cannot launch the FW49 concept blind even if you have to change concept,” he said, making the team’s ability to understand and control its current car central to its prospects of moving forward.