This year he has also taken part in pre-season and several Friday practice sessions as he continues to push for a 2019 race seat.
When asked how his most recent appearance went, he said: “It was all OK.
“We did have a bit of a mixed program with some data collection for next year, and trying to understand how we can make the car work better for next year’s car. But we did do a few runs with a current specification car as well. So the feeling was good.
“Twelve months ago I was here for the first time with Renault, and after 12 months I can say everything is easier! One year ago everything was new for me, especially with the new generation of Formula 1, and now everything is more familiar, easier and I’m more confident. So all good.”
On the second day of the test Williams ran a garish colour scheme, owing to the flo-viz aerodynamic paint on its car to measure car performance. Williams is currently rooted to the bottom of the championship table.
Kubica, who earlier this season said the team’s livery design is the car’s biggest strength, joked that it could be a colour scheme to consider for next season.
“I don’t know , it’s too early to say. It was just more for the aero guys to get more information about it and what it does to the rest of the car and how the airflow is going to be distributed differently. We did end up also with trying a new livery on the last run with new paint. It looked nice, so maybe a change for next year!”
Kubica will have to wait until November for his next appearance, in Friday practice for the Abu Dhabi Grand Prix.