The Grove-based outfit has been supplied power units by Mercedes since the start of the turbo hybrid era in 2014 but their contract will expire before F1’s next engine cycle begins. 

What is going wrong at Ferrari?

Mercedes currently supplies three teams - Aston Martin, McLaren and Williams - with power units but may have to part ways with one of their customers. 

That is because the 2026 PU regulations state that a manufacturer can only supply three teams per season, including its own factory team, “unless agreed otherwise by the FIA”. 

A final decision regarding Williams’ supply from 2026 is still pending and a breakaway from Mercedes has not been ruled out by new team boss Vowles. 

“We are still in the process of making sure we understand all the options available to the team,” said Vowles.

“The rules contain some lines which state that theoretically as taken in 2025 this is the number of teams a PU manufacturer can supply. Same rules, by the way, that should have limited [Mercedes] this year down to less PU supplies than they currently have.

“I think that's an ongoing discussion. But no, we're not locked into Mercedes. And we're still in the process of reviewing.

“But we have to, as all teams will do as well, come to a decision fairly shortly. I think end of the year would be late. So a little bit before then.”

What other options does Williams have? 

After losing Alfa Romeo Sauber to Audi in 2026, Ferrari will have an available customer slot, while Renault currently only powers the Alpine works squad. 

The aforementioned Audi would also be a potential option and so too would Red Bull Ford.

Meanwhile, Honda’s F1 future beyond its partnership with RBPT - which is due to conclude at the end of 2025 - is uncertain. 

The Japanese manufacturer has registered as one of six F1 power unit suppliers for 2026-2030 but currently has no supply deal in place. 

McLaren is said to have already held talks with Honda and Williams would be another obvious candidate. 

Vowles insisted his historical ties to Mercedes would not have any bearing on the decision Williams ultimately makes. 

“As you would imagine, it would be foolish to simply just go with where I'm comfortable and what I know,” the former Mercedes head of strategy said. 

“If you're going to get your house painted, you get three quotes, I would highly recommend you do that if you don't. And it's the same here, I want to make sure I understand what's available to us."