Lewis Hamilton believes that the reliability of the W07 Hybrid is a key strength for Mercedes after he clocked the second quickest time during testing at the Circuit de Barcelona-Catalunya.
Hamilton set a time of 1:23.622 to finish a few tenths adrift of Williams' Valtteri Bottas but hailed the mileage achieved by the team as it added another 161 laps to its tally on Wednesday.
"Reliability is our strength at the moment," said Hamilton. "The strength within the team has grown even further.
"It's really motivating for the season. The car was good, quite strong, we did some lower fuel running today but some work needs to be done balance wise.
"Getting onto the softer tyre was a good experience but we've got some work to do still."
Nico Rosberg ended in ninth spot as he focused on a full race simulation.
"The team have done a great job so far both in the factory and here on track," he said.
"The car feels great out there and I haven't had a major problem yet. I hope this will continue for the last two days."