Rival Formula One teams are set to request a rules clarification from the FIA about the design of the diffusers on the Williams and Toyota cars, this week's Autosport magazine reveals.
The two outfits are alone in having opted for a different design concept at the rear of the car compared to their rivals.
The diffusers at the rear of the Williams FW31 and the Toyota TF109 appear to exceed the maximum height of 175 mm at their peak through clever aerodynamic shaping of the rear crash structure.
Although both teams are confident that their designs are within the regulations, rivals outfits have expressed curiosity in the way their diffusers have been shaped - especially because it could give them an advantage in slow speed corners.
It is understood that several teams are looking at seeking clarification from the FIA about the matter, with Renault the first to confirm it will do so.
Renault executive director of engineering Pat Symonds told Autosport: "They (the diffusers) are certainly interesting, although I don't think I can comment on their legality.
"That's something for the FIA to comment on. We will be asking the FIA about it, but we haven't yet."
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.
The extra area of the Toyota diffuser is based in a 15 centimetre wide zone at the centre of the car where teams are allowed to fit extra bodywork. This has created a longer centre tunnel for air.
This week's Autosport magazine carries a full graphical analysis of the Williams and Toyota diffusers.
Because the regulations have changed so much this year, there is a high chance that further areas of car design will come under scrutiny over the course of the season as teams push to find loopholes in the new rules.
Teams who are concerned that an area they are developing may be questionable, can ask the FIA for a clarification about their design.
Furthermore, rival outfits can also seek answers from the governing body about the legitimacy of design features they have spotted on rival cars and may want to incorporate themselves.
An outright question about the legality of a rival car can only be lodged on a grand prix weekend, when a protest would need to be handed in to the race stewards.