Tuesday 11 December 2018 12:40, UK
Mercedes caught the eye on the first day of in-season testing at Barcelona on Tuesday when they ran the W09 with two new rain lights on their car's rear wing.
Lewis Hamilton was at the wheel of the W09 when the team debuted the fresh look.
"This is just a trial light set-up for better visibility in the rain," Mercedes explained.
Hamilton completed the equivalent of two full race distances before handing over the W09 to team-mate Valtteri Bottas for the second and final day of running on Wednesday.