What amazes me with all this is why they are legal.........it's all about twisting words around in the rules (like banning mass dampers was - but the other way around ).
I am sure that wheel covers are specifically banned (i.e. trims as seen in indy cars and also on the porsche posted earlier).
Whatever job they do, by any reasonable deduction they could be construed to be wheel covers - even if that purpose is only incidental to their real function (like hell ).
By the same token that a mass damper is a moving aero device; a fan car is in fact a sucker car in disguise. Surely these parts should be considered as sailing too close to the wind?