Monday 4 May at 10:31 : May 4 (GMM) It is not certain that a 'double diffuser' solution will be ready to be added to the 2009 BMW-Sauber package for this weekend's Spanish grand prix

"Whether it will be there or not is not yet definite," team boss Mario Theissen is quoted as saying by Germany's Sport Bild

The Hinwil based team has had a difficult start to the 2009 season, with hopes now pinned on a major upgrade for the struggling F1.09 car in Barcelona

Sport Bild claims that designers did devise a double diffuser for the single seater, but that computer simulations raised doubts about its effectiveness

The drivers, including Robert Kubica who is yet to score a single point, are not optimistic

The Pole told Sport Bild: "We will make a step forward in Barcelona, but whether it will be big enough is improbable."nnTeammate Nick Heidfeld added: "We did the first four races without big changes on the car, while the other teams constantly had new parts and went further ahead than us."n