MONZA, Italy -- As far as Ferrari's technical director Mattia Binotto is concerned, the debate over the legality of his team's power unit is "completely closed".
For the first time since 2014, Ferrari has gained a noticeable power advantage over Mercedes, and since the British Grand Prix in July has extended its margin over the world champions. The exact details of how Ferrari has extracted so much performance from its power unit in such a short period of time remains a mystery outside of Maranello, but Mercedes has been keen to flag its deficit to the media.
GPS traces of the cars on track suggests the extra performance comes on sections of the circuit where Ferrari is deploying electrical energy from its hybrid system.
Earlier this year, a thorough FIA investigation into Ferrari's hybrid system found nothing untoward and Binotto says his team has worked with the governing body to help them understand how the system works.
"Obviously, the power unit is a complex element and it has been since 2014," he said. "The FIA is fully aware of our components and it is our duty as well each time to make sure the FIA is fully, let me say, convinced that there is something right or wrong for them to inspect, to understand better.
"I think it's simply what happens at the time there is some questions: we answer; we explain and I think that's what happens. That's it.
"The FIA certainly is happy, declaring our car legal at every single race, and on our side, honestly, fully happy at seeing the point is completely closed by them."
Much was made of Ferrari's performance advantage over Mercedes at Spa-Francorchamps last weekend after Sebastian Vettel took victory by 11 seconds on one of F1's most power-sensitive circuits. But Binotto insists the race was much closer than it looked on the timing screens and believes Ferrari does not yet have a clear advantage over its rivals.
"I think the difference to Mercedes overall was very small at the end. They have been on pole in quali, so they have been the fastest car, as a matter of fact, and I think that in the race our pace was very similar. So to try to distinguish if there is a little difference, where it's coming from, is a very difficult exercise.
"Our package is working well as a whole, from the aero, from the chassis, mechanicals and the power unit and I think that as well in terms of development we are all focused on all the areas."