Red Bull, Lotus seek final ruling on Mercedes' rear wing ahead of Malaysian Grand Prix weekend

Both teams met with the FIA's Charlie Whiting over the Australian GP weekend to express their belief that the concept used on the Mercedes rear wing is in breach of regulations that prevent driver-activated aerodynamic devices.

The Mercedes design features a hole on the inside of the rear wing endplate, which is covered when the DRS is not in use but uncovered when the DRS wing lifts up.

It is understood that this hole ducts air all the way through to the front wing - where it escapes through slots in the underside to help stall it for a straight-line speed boost.

Both Lotus and Red Bull considered the possibility of a protest against the Mercedes in Australia, but elected against doing so for now because they preferred to try and sort the matter out behind closed doors.

Lotus team principal Eric Boullier said though that the next few days would be key to trying to resolve the matter in an amicable way.

"We are still talking with Charlie," Boullier told AUTOSPORT. "Of course we did not do anything here [in Australia], but we just want to have a fair understanding.

"It would have been the wrong thing to spoil the race result to be honest, so the plan is to wait for next week. Let's see what happens."

Red Bull team principal Christian Horner added: "I think that there are different interpretations of the rear wing of the Mercedes. We have had some discussions with Charlie, and we chose not to protest it this weekend.

"There were other teams who were perhaps even more animated than we were, but I think it is something that we just want clarity on because one could argue that it is a switch that is affected by the driver.

"The driver hits the button and it uncovers the hole - so therefore it is driver activated, which would not be in compliance with the regulations. I think there will be a whole load of debate about it during the next five days."

Horner said that if the FIA stands firm in its belief the system is legal, then it would likely lead to teams needing to embark on a costly development push to introduce their own versions.

"It is a clever system and hats off to them for doing it, but the most important thing for us is - is it OK?" he said.

"The frustrating thing with all these systems is that it will undoubtedly be banned for next year, but in the meantime are we all going to go off and chase the idea.

"Inevitably there would be a considerable amount of cost involved. It would be a development that the front teams would look at, but it might be something that is prohibitively expensive for the smaller teams."