James Allison insists F1 cannot say whether Fernando Alonso, Lewis Hamilton or Sebastian Vettel is the best as the trio have never been in the same car.
It is an age old debate that will continue to rage as to who is the best driver in Formula 1.
At present, the sport has three greatest competing in Alonso, Hamilton and Vettel.
While the Spaniard has two World titles and three near misses on the board, Hamilton is chasing his fourth and Vettel already has four to his name.
However, which of the three is the best.
"I get asked this question a lot and it's a frustrating question," Allison, Mercedes technical boss, said.
"First of all, there's an impossibility of answering it because there's only one way to know for sure and it's to line them all up in exactly the same equipment on the same days and have a championship where you find out exactly.
"All I can tell you is that all three of them have got the victories and the achievements that they have, not by good fortune but by being brilliantly skilful racing drivers."
Asked about working with Hamilton, who he joined at Mercedes this season, the former Ferrari man says it is definitely one of the "good things" about working at Mercedes.
"It has been a considerable pleasure joining Mercedes this year for many, many reasons but one of those was that it was my first opportunity to start working alongside Lewis, ”he said. “I think I’d only ever said hello to him once in all the years prior to that.
"The experience of working with him is very different to what I imagined it would be and I’ve found a racing driver or the sort of excellence that all of us can see from his statistics and the way he goes about his job.
"But what has been particularly good is that I’ve found a guy that conducts himself as a man in a way that makes you happy to work alongside him. And that’s been an enjoyable and good thing about joining Mercedes."
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