Valtteri Bottas says Mercedes would have “struggled massively” on Friday at Hockenheim had it not undertaken work to address its cooling concerns.
Mercedes’ sole defeat of the 2019 season came at the Austrian Grand Prix last month as it struggled to cope with the hot weather.
It opened up as much of the bodywork as it could on the W10 and later conceded that its small radiators were also a contributing factor.
Mercedes introduced revisions at Hockenheim and they were much-needed as the temperature peaked at 38Ëšc on Friday afternoon.
Ferrari finished 1-2 in both sessions on Friday but Lewis Hamilton was a close third, with Bottas – having narrowly avoided the barriers following an off in FP1 – in fifth.
“We've made some progress on our cooling; we would have struggled massively to run here with the package we had in Austria, but with the new package we could actually complete some good long runs,” said Bottas.
“The weather is going to be completely different tomorrow and on Sunday with lower temperatures and a chance of rain.
“So we will need to be very dynamic reacting to the weather with the car set-up. We haven't really run in the wet this year, so I actually hope for rain – it would be nice to drive in the wet.”
Hamilton added: “It's not been the best of days in terms of the heat, but pretty straightforward otherwise.
“These tyres don't like the temperature so we had to do very slow out-laps and the tyres don't last very long. It's all about trying to keep the tyres in the working range.
“They were always overheating, so that's been the main issue today, but we're all in the same boat.
“We're hoping the weather won't be like this for the rest of the weekend. If it's cooler and it's dry, nothing from today really applies – the tyres will come back towards us and everyone will be quicker and more comfortable on the track.”
