After uncertainty about Mercedes' competitive situation following testing, Hamilton and team-mate George Russell endured a difficult opening day of practice in the Bahrain Grand Prix.
Hamilton ended the more representative second practice session down in eigth place, five places ahead of Russell.
But with the new W14 lacking performance against pace-setters Aston Martin and Red Bull, Hamilton was downbeat about things on Friday evening.
Asked what he had found out on track, Hamilton said: "We've found out we're a long way off.
"We kind of knew that a little bit in the test, but it's a big gap. I'm trying everything I can out there."
Hamilton said Mercedes was losing time to its rivals in both high-speed and low-speed corners, as he reckons Red Bull's race pace put it one second per lap up the road.
After enduring a difficult start to last season, as Mercedes struggled with the W13, Hamilton believes things had the potential to be even worse this year as he suggested the squad had been leapfrogged by Aston Martin.
"I thought that Ferrari were second," he said. "But I think on the long run, we're quite close to Ferrari, and it looks like the Aston was second.
"We're kind of between third and fourth. So we're kind of either where we were last year, or if not a little bit further behind.
"It's difficult for everybody. And this is really not where I think anyone in the team wants to be, and certainly not where I believe everyone deserves to be, because everyone continues to work so hard and really are so courageous and thoughtful in the process.
"We're just on the wrong track. So we've got to just continue to graft away and find a way to get ourselves on the right track. But right now, we're a long way off from the guys in front."
And while Hamilton fully understood the progress that Mercedes was able to make last year as it got to grips with its porpoising car, he suggested that the current pace was the maximum from its current car concept.
"I have to be hopeful," he said. "I think there was good progress through last year, but the gap wasn't as big as it is now.
"Do I believe we can close the gap at some stage? Yes, but I think it's quite hard with the concept we have."
Hamilton's concerns about the state of his car mean he is not optimistic about being able to make any major progress over the remainder of the Bahrain GP weekend.
"I think I've got the car to the best place I can get it, set-up wise," he said. "We'll continue to tweak little bits here and there. But it's going to be small bits here and there, which is milliseconds. It's not going to be closing of the gap of a second.
"But nonetheless, we just keep our head down tonight and we'll go through the data. We will continue to work and try to progress tomorrow, but we have got to try and find out if there's any way we can have performance overnight."
