Given that he only drove in the afternoon, we'll label Valtteri Bottas as Tuesday's marathon man, with the Finn covering 102 laps around the Circuit de Catalunya.
While Lewis Hamilton's morning work with Mercedes focused on aero data collection, soft tyre compound analysis and general setup work, the Finn completed a race simulation before rounding off the day with further aero tests.
"I think it was another good test day for the team," said Bottas.
"We did so many laps again and completed all the runs that we had planned to do. I worked on race simulations this afternoon. It was quite tricky with the windy conditions but I'm sure that we can learn a lot from the data."
Mercedes new recruit had a big moment at Turn Nine but fortunately remained clear of the barriers!
"I had a small off but it wasn't anything serious. I lost the rear end with a gust of tail wind that was quite sudden. This is testing - you need to find the limits."
Half-way through the first week's programme, there hasn't been a worry insight for the Silver Arrows squad which continues to dial in its potential.
"It's interesting to learn more about the new car - not just for me personally, but for us as a team. All the set-up work we've done has been very valuable. Two more days to go - I'm looking forward to it."
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