Williams has taken a step forward in Miami after a difficult start to 2026, with a key part of its upgrade focused simply on reducing weight.
Driver Carlos Sainz said the car is at least more competitive than before the April break.
"The good thing is that we were able to recover," he said.
"We were faster than the Haas cars, which we weren’t five weeks ago, so it’s positive."
However, as a GPDA director, Sainz also played down the impact of the new regulation tweaks, designed in part to appease the increasingly-critical driver contingent.
"Very little has changed. We knew very little would change," he said.
"We’ll have to wait until later in the season, or even next year, for the FIA and the teams to dare to make bigger changes."
Behind the scenes, much of Williams’ progress has come from a major weight reduction program.
Team boss James Vowles revealed the scale of the effort.
"The engineering work they’ve completed at the factory has removed all the weight from the car plus 10 kilos," he said.
"That’s the engineering work that’s been completed - it hasn’t been delivered to the car because, with the current cost cap, it’s no longer efficient to do so."
Instead, the improvements will be introduced gradually.
"As for the weight, it’s a couple of kilos (in Miami), and there will be a similar reduction at each race, basically," Vowles explained.
"You have to be careful when taking a product to the track when it’s practically out of production."
"But what pleases me is that it has already been shown that we can design the car to the right level so that it has the correct weight."
"That’s what we’re aiming for, but production will take some time."
He even joked about the gains, rubbing his stomach when referring to the "couple of kilos" saved in Miami.