Lewis Hamilton says Mercedes spent much of testing trying to understand its car after admitting it never had the "perfect day" despite showing good pace and encouraging reliability at the Circuit de Barcelona-Catalunya.
Hamilton's best lap was six-tenths slower than Kimi Räikkönen's overall headline-grabbing time of 1:18.634, and admits the team is yet to understand how to get the most from its W08.
However, Hamilton is convinced that he could have set a quicker time, and remains sure that Mercedes can make strong progress.
"Do we have more potential? I mean time will tell," he said. "We’ve been focusing on trying to understand this car and getting the most out of it and as I’ve said, there’s never generally been the perfect day, but there’s more potential in the car for it to grow.
"Every year in testing, you don’t necessarily go as quick as you can and sometimes there are times when teams hide potential by sandbagging, but I don’t really see that [tactic] as being a benefit to the team.
"I didn’t feel like I got everything out of it [the car], so I could go faster, but of course there are all sorts of things that can bring the time down [such as fuel load]."
Hamilton does however feel Mercedes made progress on the final test day, adding: "We did everything we needed to do and learned a lot, which is always a positive as some days you don’t learn a lot.
"You chase your tail sometimes. But we learned a lot. I feel confident we’ve got everything we need from this test."