Hamilton has been testing McLaren's MP4-24 in Spain
Lewis Hamilton admits McLaren have a great deal of work to do if they are to be ready for the Australian Grand Prix.
The reigning Formula One world champion is currently testing McLaren's new MP4-24 in Spain, ahead of the season-opening race in Melbourne on 29 March.
"I haven't arrived here thinking I'm world champion, I've arrived thinking I've got a great team I need to push as hard as I can," said the 24-year-old.
"We've got a lot of work to do to make sure we're ready for Australia."
Hamilton admitted in January he was facing a race against time to get to grips with the technical changes Formula One will embrace this season.
McLaren is one of the teams using kinetic energy recovery systems (kers) - one of the many changes that are being introduced for 2009 - in its two cars.
The Renault doesn't look bad, the BMW doesn't look bad, so there's quite a lot of teams looking pretty impressive at the moment
Hamilton and former world champions Fernando Alonso of Renault and Ferrari's Kimi Raikkonen were among those testing on Wednesday, the fourth of five development days.
Alonso headed the standings on a windy day, clocking one minute 19.945 seconds - the third best time of the week and 1.357secs quicker than Hamilton, who could only finish seventh of eight overall on his return to the track.
"I'm very happy with the result from this test as we had two trouble-free days, a very consistent car and the work we have done has been very useful," said Alonso.
Raikkonen was second quickest, just over three tenths of a second down, followed by Nick Heidfeld for BMW Sauber and Toyota's Jarno Trulli.
Red Bull's Mark Webber and the Williams of Kazuki Nakajima also finished ahead of Hamilton, who only managed 70 laps.
On Sunday, Red Bull's Sebastian Vettel outpaced last year's championship runner-up Felipe Massa with his fastest lap of one minute 19.055 seconds, nearly 1.3 seconds ahead of the Ferrari driver's best effort.
Massa was followed by Toyota test driver Kumui Kobayashi, Williams' Nico Rosberg and BMW Sauber's Robert Kubica.
"Just from looking at the times it seems like they (Toyota) are doing quite a good job but I think a lot of the teams are doing quite good jobs," said Hamilton.
"The Renault doesn't look bad, the BMW doesn't look bad, so there's quite a lot of teams looking pretty impressive at the moment.
"This is my first day of McLaren and Ferrari being at the same track but for me it looks very similar to every other year. Everyone's times are looking good - some consistent, some not."
Hamilton added that the MP4-24 felt pretty similar to last year's car.
"We have less down force and the tyres have slightly different characteristics but otherwise it's all very similar, he said.
Heikki Kovalainen, Hamilton's team-mate, said he was "99% confident" McLaren would be using kers in Melbourne.
The system provides drivers with a short burst of power on each lap from energy stored under braking.
Despite teething problems, McLaren appear in an advanced stage of development compared to a number of their rivals who have made it clear they will not be using kers at the Albert Park circuit.
"Hopefully it should be an advantage for us. Certainly it's going to potentially give you a big benefit from the start to the first corner," said Kovalainen.
"My feeling comes from how well we're operating it at the track, and that's why I'm 99% confident we should be using it.
"We are now hitting a stage where we can run it all day, reliably, without any problems, at the maximum power. So unless something goes dramatically wrong, I don't see a reason why we shouldn't run it.
"Hopefully other people don't get it and we get it, but there are other good teams around and I wouldn't under-estimate anyone. I wouldn't be surprised if many of the other teams had it as well."
Ferrari, BMW Sauber and Renault are also hoping to use kers in Melbourne.