Mercedes drivers Lewis Hamilton and Nico Rosberg have hailed the outfit's start to the 2016 season after the W07 Hybrid completed four full days of running during the first test.
Hamilton and Rosberg collaborated to complete over 10 Grands Prix worth of laps at the Circuit de Barcelona-Catalunya, conducting more running than any other team.
While the pair never topped the times at the end of the day, Mercedes spent the test completing laps on the Medium compound tyres and focused on reliability and race simulations.
"The reliability of the car this week has been just incredible," said Hamilton.
"It feels strong, it feels solid, it just keeps going and going... I've never seen anything like it. The guys and girls at Brackley and Brixworth have done an unbelievable job.
"After two titles in a row, it would be so easy to lose focus. But it's clear that everyone is even more focused than before and have done an even better job of delivering an overall package with this car."
Rosberg echoed Hamilton's comments after completing the afternoon session on Friday.
"It's been a great start," said the German, entering his seventh year with the team.
"Reliability is looking very, very good and the car feels quick. It's great even to look at. You take a walk around it and there's some real innovation there.
"You can really see how far we've come as a team these past few years - it's very impressive."