On the back of its struggles at the Austrian Grand Prix, Mercedes has worked hard on a series of developments to improve the cooling of its car – which has been marginal all season.
The timing of the introduction of the new parts could not have been more important, with Germany taking the full brunt of the heatwave that has spread across Europe as temperatures got close to 40C.
Asked about how much the updates had helped, Bottas said: “I think we have made progress. I think with the package we had in Austria, we would have struggled massively to run.
“But now we could complete some good long runs and it is going to get a lot better on Saturday and Sunday with the temperatures, so it is good to see we have been able to improve that.”
The Finn added that the experience of driving in the heat in Germany was something he had not encountered before in his career.
“It was extremely hot,” he said. “I cannot remember driving in these kind of conditions. But anyway, it is the same for everyone.
“It makes it more tricky for the drivers and the cars and tyres, lot of overheating especially in sector three with the corner combinations.
“It becomes so sensitive. You slide a bit more and you pick up 10 degrees of extra tyre temperature and you can lose a few tenths like this. So quite sensitive.”
With cooler temperatures expected for the remainder of the weekend, and rain even possible, Bottas says that there is little to take away from the Friday times as rival Ferrari led the way.
“It is going to be completely different, and could be rain on the way and same on Sunday,” he said. “It is a day we need to be very reactive and dynamic with the weather and car setup.”
Teammate Lewis Hamilton added: “I don’t feel we learned much today. It was so hot, and if it is cooler or not dry nothing from today applies [for the rest of the weekend]. The tyres will come back towards us and everyone will be quicker and more comfortable, but we wait and see.”