Ferrari failed to win a race last year, dropping to fourth overall, and seven-times world champion Hamilton suffered his first season without a single podium appearance.
They are hoping to be far more competitive this year, the start of a new engine era with the biggest rules reset that any of the drivers have experienced, although Mercedes are already looking ominously reliable.
"When you come to the test you always want to get a lot of mileage," said Hamilton in an interview with Formula One television on Thursday. "Like, today I did 85 laps in the morning which is amazing.
"Last year we had a worse start to testing. So this, considering it's a completely new band of rules, it's better than we've experienced in the past. So I'm really hopeful that continues."
All teams must choose three of five days to run their new car in the behind-closed-doors test in Barcelona, with Ferrari opting for Tuesday, Thursday and Friday.
Thursday was Hamilton's first proper dry day in the car after rain hit Tuesday's session, when he and teammate Charles Leclerc were both in action.
Hamilton said he had got through his programme, before handing over to Leclerc, and had a "bit of an understanding of where the car is at and where we need to improve".
The Briton is in his second year at Ferrari after joining from Mercedes at the end of 2024.
Formula 1 teams have two open tests in Bahrain next month before the season starts in Australia on March 8.
