©XPB Images
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.
©XPB Images
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
Mercedes has identified the underlying cause behind a series of costly retirements that have disrupted…
Reigning Formula 1 World Champion Lando Norris believes George Russell’s fight to keep pace with…
Six cars. That was the full extent of the starting grid at the US Grand…
Aston Martin reserve driver Jak Crawford is set to return to Formula 1 action at…
The Formula 1 paddock may not have to wait much longer for answers about Max…
When Carlos Sainz signed for Williams, it was billed as a bold leap of faith…