Valtteri Bottas says his Mercedes heat-generating black overalls were partially to blame for the weight loss of 3kgs he endured in the Spanish Grand Prix.
Sunday's race took place in scorching hot conditions and while the 66-lap event only included one retirement - Ferrari's Chares Leclerc - and no specific tyre issues, the Barcelona round was physically taxing.
In the opening stages of the race, Bottas radioed in to complain about the heat, commenting that "these black overalls are f**king hot."
Mercedes switched the colour of its car and team kits before the 2020 campaign got underway to reflect its commitment to diversity, with Lewis Hamilton and Bottas trading their usual white overalls for black suits.
But the change has apparently boosted the heat inside the cockpit of Mercedes W11.
"It was really hot in the car," Bottas said after Sunday's race which he finished third.
"This year, it's been even hotter in the car. Obviously, we had to change the colour of the overalls. And it's known that black colour takes more of the heat, especially when there's direct sun.
"I don't know any number or facts, how much actually black versus white is in terms of temperature difference, but this year, it's been really hot in the car. And also there's a new homologation this year for the overalls, so they are thicker, and the underwear is thicker, so I don't know how much effect that has."
Bottas says the resulting body temperature increase could ultimately impact a driver's performance.
"It was just so hot so I said, ‘Guys, you know that these overalls are way too hot.’ And for sure, white would be cooler in terms of temperature and today for example I lost three kilos in the race, which is quite a lot.
"And that's where it can start to affect performance. I know that from all drivers I'm one of the fittest if not the fittest, so I can take it, but it's never comfortable and there's always things that we can improve."
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