Williams is conducting a filming day at the Circuit de Catalunya on Friday, as it uses the opportunity for extra mileage after the first week of testing.
The team's 2019 challenger only arrived at the track early Wednesday morning, due to delays with new parts. The car hit the circuit for the first time later that afternoon, but was already two and a half days behind the rest of the field.
Throughout Wednesday and Thursday, it managed to clock 88 laps with its drivers George Russell and Robert Kubica behind the wheel.
Teams are restricted to 100 km of running at filming days. The Grove squad is sharing the track with Racing Point and McLaren for the day.
The second week of testing will kick off next Tuesday, and Russell says that a lot of work needs to be done to make sure it has a smooth second week of running.
"It was important to get some mileage under our belt and get a feel for the car," he said. "I've only done eleven proper laps in the car but it still gives us an understanding of where we're at, the limitations, at what we need to work on for next week.
"It's definiely not in its full state. We've got some ork to do to optimise everything. Beause it was all last minute, things werent 100% and it was a matter of trying to get on track in any means possible. We need to work really hard this weekend to make sure we hit the ground running next week to try and rack some miles up."