London: Lewis Hamilton talked down his Formula One title chances on Wednesday, describing the new McLaren as a let-down that was still some way off being a winner.
The 2008 world champion made clear that McLaren had missed a trick and were playing catch-up, with time running out before the start of the season.
"Do I believe I have a car to win the world championship at the moment? I don't. No." the 26-year-old Briton told reporters after a difficult day in the car at the final pre-season test in Barcelona.
"We should definitely have been able to have continued from '08 and won another championship in the last two years, but we haven't.”
"Looking at how the car has developed over the winter and seeing how it has come out, I was really, really excited getting into it thinking we really had hit the nail on the head," he added.
"But we've missed that nail a little bit, although it's not like we don't have any other opportunities to get it right."
McLaren finished runners-up to champions Red Bull last year but had hoped to close the gap significantly with their new car. Instead, they have been off the pace and struggling with reliability at the tests in Spain.
Hamilton was only fourth fastest on Wednesday, with his best lap more than a second slower than Red Bull's champion Sebastian Vettel.
More worryingly, he did just 57 laps to Vettel's 112. Toro Rosso's Swiss driver Sebastien Buemi, who was second quickest, did 120 laps.
"It has been a tough day in the sense that we've not done enough miles," said Hamilton, whose team last won a constructors' title in 1998.
"I came here hoping to do more laps, to get in a good 100-odd laps, to get in a race distance. Usually at this time of the year this is when we come with pit stops and one or two race distances a day, but we were nowhere near even completing one."
The car suffered hydraulics problems and an exhaust failure on Wednesday. One positive, Hamilton said, was that some of the upgrades tried out seemed to be an improvement.
However, the Briton now has just one day of testing remaining, with team mate Jenson Button in the car for the other day, before the start lights go out for the opening race in Australia on March 27.
"In terms of how long the car can go in terms of reliability and our true pace, that's an unknown factor for us because in the time we have had we've not been able to maximise things," Hamilton said.
"That's no-one's fault, just issues you have in testing, and this is testing, this is what it's all about, finding where your weaknesses are so you can build on them and fix them.”
"We've been focusing on those, but we definitely have several issues that are not as easy to rectify as we had hoped."
The driver refused to write off his championship altogether, saying the Mercedes-powered team could close the gap and turn the car into a true contender.
"As long as we pick up a good few points in the first few races, then we won't be miles behind," he said.
"Say for example we were able to be in the top five for the first three or four races, get those points, and then if we happen to have a car capable of winning, then it would still be possible.”
"So I'm definitely not shutting the year off. Everything is still to play for ... I'm never one to give up. I'm not going to sit here and say the championship is over blah, blah, blah.”
"I'm ready, and when the car is ready I will be at the front and I will win races," he said. "But whether that will happen, we'll see."