Sainz: Part Quality Is Williams' Biggest Weakness
Williams built the parts. Williams cannot explain why they do not all behave the same. That, says Carlos Sainz, is the real problem.
Carlos Sainz says Williams' biggest weakness is no longer car concept or weight, but the consistency and quality of the components coming out of the factory.
The newly re-signed Spaniard is enduring another awkward weekend at Zandvoort, and says apparently identical parts are not always behaving alike.
What is actually holding Williams back in 2026?
Not the concept, in Sainz's view. The production line.
"What we need to learn as a team is how there is so much variability between parts of the car, and we don't understand why," he told Spanish media.
"Quality and production control of parts is one of our biggest weaknesses as a team and in general, and it's where we need to improve the most next year, I'd say."
"More than the weight issue, it's the quality control of the parts. There are still ghosts of the past in the team that we have to eliminate, because it's clear that we struggle a lot on race weekends."
Do two identical floors really behave differently?
According to Sainz, yes.
"Yes, we do have more floors like that one, we have many of those versions, it's just that each floor does a little bit of what it wants," he said.
That is a brutal sentence for any technical department to read, and it explains why the team's understanding of the new-generation car keeps slipping.
"We have a lot to learn as a team because you change one thing and it gives you the opposite. We need to find several issues that are holding us back if we want to compete next year."
"It's very difficult to make any progress next year without understanding the car."
How close did Williams come to losing Sainz?
Closer than the eventual contract announcement suggests.
Team principal James Vowles admits the risk was real.
"We were worried about losing him because he's a world championship-calibre driver," said the Briton. "He deserves the opportunity to fight for podiums and more."
"We didn't give him the opportunity to fight for everything, even though we had a clear vision. Taking a step back carries the risk of losing drivers, but I appreciate that they've remained supportive."
What does Sainz get out of staying?
Very little in the short term, and he is not pretending otherwise.
"Honestly we're fighting for 17th, 16th, 15th."
"So, as a team, we're focusing on learning, investing, and trying things that will improve us next year. When you've been fighting for wins in F1, it feels so insignificant that you prefer to invest in the future."
It is the classic bet of a driver in his thirties: trade two seasons of scoreless Sundays for a competitive car at the other end. The 2026 standings show exactly what he is paying for that bet.
Quality control is an unglamorous thing to name as your headline problem. It is also, unusually for F1, one a team can fix without a rule change.
Related: Sainz Commits to Williams Despite 'Flawed' Car
