Red Bull still fighting FIA over controversial ADUO ruling

Red Bull has revealed it is still trying to overturn the FIA’s controversial ADUO engine assessment, insisting the governing body is continuing to review the data.

The ADUO system has become one of Formula 1’s biggest technical talking points after Red Bull-Ford was judged to have the strongest combustion engine, leaving rivals Ferrari, Audi, Honda and even Mercedes eligible for varying levels of additional development.

Team boss Laurent Mekies indicated the matter is far from settled.

"We have been having very constructive discussions with the FIA ever since," he said, when explaining the team’s shock at being found to have the strongest engine in the field.

"They are doing a review, we are exchanging as many data as possible to make sure they get the right picture and the full picture."

"As you said, not only do we feel differently about this outcome, but also it has large implications for this year and for next year. So, it’s important, first and foremost for the sport, that we get that right."

"Obviously for Red Bull Racing, the impact of being on one side of the fence or on the other side of the fence will be large."

The FIA has yet to publicly confirm the final ADUO rankings, leading to speculation the initial assessments remain provisional and could be reviewed again at the Hungarian GP - the last race before the summer break.

Audi boss Mattia Binotto stressed that the FIA’s assessment is based solely on combustion engine performance rather than the entire power unit.

"It’s not related to energy management, efficiency of the electrical system," he said. "It’s pure engine power."

"If you have been assessed that you are down in engine power, I think the first where you have to be concentrated and focused is really on engine power."

"There are certainly efficiencies in the batteries, in the inverters, in the turbo dimensioning for what can be drivability on track and compromises. But certainly when it comes to ADUO, that’s assessing the gap on pure engine power."

Mercedes boss Toto Wolff agreed.

"It’s internal combustion engine, as Mattia said," he said. "I think it’s quite easy to analyse."

"You can see how much grunt you have from the ICE. And definitely being behind is a challenge for us."

However, rumours in the paddock now suggest Mercedes may delay using its own ADUO allowance for now, despite qualifying for the concession.