These fins on the Williams and on many different cars in the ‘80s weren’t aero devices, but just “shadow plates” for the mirrors required since 1983 till the moment (1989 ? possibly later) the flat bottom rule : “while viewed from below, any part of the car between the read edge of the front wheel etc, must lie on a flat plane”, was changed in “while viewed from below, any part of the car, bar the rear view mirrors etc...”klippe wrote: I also recall that as far back as 86/87 the Williams cars (FW11/11B) had small 'tabs' just ahead of the cockpit area (attached to the floor of the car) which seemed to be there for vortex generation reasons. They were so small that they seemed to be almost a waste of time, but they kept running them, so they must have been there for some reason.