Williams is testing a radical rear wing design during the opening day of the post-race at the Circuit de Barcelona-Catalunya.
Alex Lynn took to the circuit with a rear wing which featured additional wings above the standard design. The front wing also features some additional components, with Williams telling F1i the designs are "to gain a better understanding of the car aero balance over a lap" and relevant to both this year and 2017.
The design is not legal under the current regulations but teams do not have to pass FIA scrutineering during testing and can therefore run whatever they choose.
Williams has yet to score a podium this season, and is currently fourth in the constructors' championship behind Mercedes, Ferrari and Red Bull.
LIVE: Barcelona post-race test - Day 1
DRIVER RATINGS: Spanish Grand Prix
Breakfast with ... Claire Williams
Keep up to date with all the F1 news via Facebook and Twitter
Sebastian Montoya, the 19-year-old son of former Formula 1 star Juan Pablo Montoya, is set…
When former Ferrari team principal Mattia Binotto took on the role of Chief Operating Officer…
Charles Leclerc concluded the 2024 F1 season with a sense of satisfaction, the Ferrari driver…
Former Formula 1 driver David Coulthard has voiced his dismay at FIA president Mohammed Ben…
Super Aguri's application to join Formula 1 became a reality on this day in 2005,…
Ferrari roared back into contention in 2024 to deliver their strongest season in years, thanks…