Looking at the Ferrari Spanish GP rear wing with its literal interpretation of the slot gap separators, it brought to mind another rear wing designed to work around the rules. Back in 2004 the FIA introduced a further limit on upper rear wing elements, going down from three to just two elements, a rule that stands to this day. In 2003 teams ran with what was often called a bi-plane rear wing. That is the three elements were mounted as: a two element wing (main plane and flap) and a further element cascaded above them. When two elements were mandated, the wording in the technical regulations was vague and defined what constituted the two closed sections by defining how large a space was allowed between them. This left some opportunity for a different interpretation. Willem Toet was then the Head of Aero at BAR Honda, he and his design team found a way to make a three element wing meet the wording of the two element wing.
By joining the three element wings cascade element to the flap with twisted vanes, the cross section of the assembly always met the FIA definition of a closed section. Each of the 20 vanes joind the two wing elements such that any cross section always had the upper and lower elements joned by part of a vane. This met the rules, just as the fishbone exhaust outlets in 2009 or the F-duct slots in 2010 met the closed section rule.
This high downforce wing was initially envisaged for a Monaco Debut, but was already prepared before the car was launched. BAR had planned a media launch day at Barcelona, as was often the practice back in those days, the teams reserved the track the day before for a shakedown and filming. Taking this opportunity to test the wing the team ran the 20-3 element design for several laps and then hid it away from the media arriving for the launch the next day. Un be known to the technical team, these laps were photographed and filmed for the teams official website and PR material. At one point it was said this “secret” rear wing was on the front page of the BAR Honda website! Once discovered the public images were removed, but BAR feared the secret was out. The wing was track tested at Silverstone by Anthony Davidson. I was unaware of the wing and only noticed the vanes when reviewing the photographs. Although I recalled that the team were fitting a gurney to the car at the time that had slots cut out. At the time I thought this was to allow the carbon fibre gurney to flex around a curved wing. Then my first inspection of the images made me think that a gurney with 20mm serration was being tested. Only later did I discover the 2-3 element wing was being tested and the reasoning behind it. However BAR feared a protest would be lodged if they raced the wing at Monaco so it never appeared at the principality.
Later in the season BAR innovated again with deep fences being fitted to the rear wing, both these and the 2-3 element wing prompted clarifications from the FIA on variation in aspect ratios of the rear wings cross section. Although not published, these demands probably still stand today.