Both the Williams FW31 and Toyota TF109 seem to have diffusers exceeding the legal height of 175 mm imposed by the FIA for 2009. After technically reviewing the two cars, Autosport revealed that the systems used by both teams are slightly different from the ones used by the other teams in the F1 paddock.
“The Williams diffuser has a low centre section, well below the 175mm height limit, before a higher steeper element further back creates a second section around the rear crash structure,” said the report from Autosport. As for Toyota, it seems that their 2009 challenger's diffuser “is based in a 15 centimetre wide zone at the centre of the car where teams are allowed to fit extra bodywork”, according to the aforementioned source.
As in Ferrari's case with the allegedly illegal exhaust system, a team official has been asked to comment this design. Renault's technical director Pat Symonds admitted that, while not being authorized to talk about it, he will advise FIA to look into the matter as soon as possible.
If found “guilty”, both teams will have to revise their aerodynamic package for 2009. This would be the second time an F1 team would be suspected to find loopholes in FIA's new rule book to get ahead of the competition, as Ferrari were also reported to be using an illegal exhaust system on their brand new F60 car. Unlike other teams – and contrary to the FIA rules – the Ferrari F60's exhaust pipes are uncovered.
Neither Ferrari nor Toyota & Williams have yet commented on these matters. In all cases, the FIA is expected to give some verdicts, as neither of the 3 teams is likely to renounce their systems unless required.