An interesting article on the Mercedes W10 from Racecar Engineering:
https://www.racecar-engineering.com/art ... ng-update/
Excerpt:
"As ever with pre-season testing the question is how fast are all the teams? However, pre-season testing, particularly in a cold Barcelona is not going to give you the answer. Aside from the teams keeping their cards close to their chests, the track conditions are unrepresentative due to the cold temperatures, so the pace of these cars will be drastically different when we get to a race weekend. This is highlighted by the cold graining shown on the front left tyre of the Mercedes W10 on the second day of testing."