Lotus and Red Bull Racing's complaints that the DRS-activated F-duct on the Mercedes rear wing is illegal have been rejected by the FIA, AUTOSPORT has learned.
The two outfits wanted clarification on the matter ahead of this weekend's Malaysian Grand Prix, with both teams reckoning the duct that helps stall the Mercedes wings for a straight-line speed boost is a breach of the rules that prevents driver activated aerodynamic devices.
Discussions between the FIA and all the teams involved have taken place throughout Thursday in the Sepang paddock, but the governing body has not changed its stance on the matter.
The FIA informed the outfits that it remains convinced that the concept is legal because it is passive, and there is nothing in the rules that outlaws a device that is activated by movement of the DRS.
FIA race director Charlie Whiting, who is head of the F1 technical department, said in Australia last weekend: "It is completely passive. There are no moving parts in it; it doesn't interact with any suspension. No steering, nothing. Therefore I cannot see a rule that prohibits it."
The news means that Red Bull Racing and Lotus - the two teams most unhappy about the design - must now choose to either challenge the matter with an official protest in Malaysia this weekend, or go ahead and develop a similar system themselves.
Mercedes-Benz motorsport boss Norbert Haug confirmed that his team's car would be unchanged from how it was in the Australian Grand Prix.
"This car passed scrutineering and got the green light," he said in Malaysia.