Following the debate over the legality or otherwise of the - subsequently modified - exhaust outlets on Ferrari's F60, the similarly contentious diffuser designs on Williams and Toyota's new challengers have reportedly been ratified by the FIA.

The rear diffusers on Toyota's TF109 and Williams' FW31 are markedly different to those on the other 2009 Formula 1 cars to have thus far seen the light of day, which prompted some rivals to request clarification from the sport's governing body regarding their legitimacy. Whilst both cars are Toyota-powered, it is unclear as to whether there was any collaboration between the two teams on the matter.

According to the new aerodynamic regulations, the rear diffuser must not exceed 175mm in height, but it has been contended that the sculpting of the rear crash structure on both cars has been shaped in such a way as to make the diffusers more than 175mm tall, UpdateF1.com reports.

'Toyota's diffuser makes a very interesting interpretation of the revised 2009 rules (and one that has already prompted speculation regarding its legality),' reads a technical analysis on the official F1 website. 'By exploiting regulations that allow extra bodywork within a 150mm zone in the centre of the car, the team appear to have cleverly shaped the TF109's rear crash structure so that it effectively lengthens and heightens the diffuser's central section, which also features a very low splitter at its base.

'Like engine supplier Toyota's, Williams' interpretation of the revised diffuser regulations is highly innovative. Much of the diffuser's central section is actually lower than the outer sections. However, clever shaping of the rear crash structure immediately below the rear light effectively creates a second central section. In combination, the result is a central section that exceeds the 175mm height allowance that applies to the diffuser alone.'

Whilst the FIA has not commented publicly on the issue, Swiss publication Motorsport Aktuell claims that both designs have been approved as meeting with the letter of the law, with Williams and Toyota having separately been told by the governing body that there is no problem. The two teams are understood to have taken advantage of a loophole in the regulations regarding extra bodywork not intended for diffusers.

Any official protest cannot be lodged until the cars are presented for scrutineering for the curtain-raising Australian Grand Prix in Melbourne at the end of March.