McLaren is to join next week's FIA Appeal Court Hearing into Formula 1 diffuser designs in an official capacity, motor racing's governing body has confirmed.
Ferrari, Red Bull Racing and Renault are taking their protest of the diffuser designs of the Brawn GP, Toyota and Williams to the FIA's highest court next Tuesday (April 14), with the concepts having so far been declared legal by race stewards.
As well as those three teams, BMW Sauber last week announced that it was also to join the hearing as an affected party, and now McLaren has also asked to be heard.
The three teams at the centre of the dispute have long insisted that their designs are wholly within the regulations - despite the complaints from their rivals.
Williams co-owner Patrick Head said in Malaysia last week that he believed rivals were only upset about some teams using the diffuser concepts because they had not thought of it themselves. He said, as far as he was concerned, the rules were clear in terms of what was and was not allowed.
"From our point of view it's very well defined and we're happy with it," he said. "As were all the teams. The TWG (Technical Working Group) spent an enormous amount of time on every detail of the rules.
"They weren't written by the FIA they were written by the teams. Charlie Whiting would go to the teams and they would say 'no we're not happy with this.' The teams have participated with the FIA to write these technical regulations."
Head also confirmed that Ross Brawn offered teams the chance to cut off the ability to exploit this area of car design with a regulation change last year.
Head said: "Ross Brawn representing Honda raised in the TWG said we are getting quite a bit more than the 50 per cent downforce and they wrote in a proposal that closed off the possibility of doing what the three teams are doing.
"But it was actually Pat Symonds who said 'no', that would be too restrictive. And he said that he did not approve those proposals.
"Ultimately the teams are presented with a set of written regulations and the intention and the spirit of the OWG (Overtaking Working Group) rules were not to allow funny bits in front of the sidepod and little guide vanes.
"But because the rules were written with exclusion boxes of certain sizes, you see most of the cars have appeared with a vane of a certain size down the outside of the sidepod and a guide vane in there. It's a little bit of opportunism, as they haven't exploited the written word of the regulation of the diffusers.
"I hope it will all be made clear after the ICA hearing on April 14th. Then everybody will understand and make sure it's clear. I'm sure there were a few hurt egos too, if someone can find a way of optimising their car from the regulations that others could not find. We're given a set of rules and we have to design our cars to the rules."