(Reuters) - Formula One teams wrapped up pre-season testing in Bahrain on Sunday with Lewis Hamilton on top of the timesheets and his Mercedes team looking clear favourites for the opener in Australia on March 16.
The 2008 world champion completed 70 laps of the Sakhir circuit and ended the final day with a time just 0.02 off the best lap of the week set by Brazilian Felipe Massa for Williams on Saturday.
"This has definitely been the most challenging winter I've experienced and the car is still very much a work in progress," said Hamilton, whose team did more laps than any other over the 12 days of testing in Spain and Bahrain.
"But we've learnt a lot over the course of these last few weeks and overall it's been a good winter of testing for us."
Formula One has undergone the biggest technical revolution in more than 20 years, with the introduction of a new turbocharged V6 engine and energy recovery systems.
"There's so much to learn with these new cars; it's just mind-blowing and I don't think anybody can be fully ready for the challenge of this season," said Hamilton. "But I feel as ready as I can be and I'm looking forward to seeing where we are in Melbourne."
Williams were second fastest on Sunday but recorded more mileage than anyone else on the day, with Finland's Valtteri Bottas chalking up 108 laps.
Ferrari's Fernando Alonso was third and did 74 laps in a session that was extended by half an hour to allow teams to test under the floodlights which will be used for next month's night-time Bahrain Grand Prix.
RED BULL BEHIND
While Hamilton can head for Australia with his confidence high, champions Red Bull have plenty of catching up to do.
Four-times world champion Sebastian Vettel recorded his highest single day mileage of the pre-season period with 77 laps completed but was 4.190 seconds slower than Hamilton's best time of one minute 33.278 seconds.
The German has also yet to complete a race distance in testing as Red Bull struggle to get their car working reliably with the new Renault power unit.
"We cannot do the times that the guys at the top are doing for a couple of reasons, but at the moment we have bigger problems to solve than just the pace," said Vettel.
"But surely things will calm down. We have to use the two weeks that we have until then to fit new parts to the car and build it to the best knowledge that we currently have."
Lotus, who missed the first test at the Jerez circuit in southern Spain, also recognised they had plenty of catching up to do.
Frenchman Romain Grosjean managed only 32 laps and was last on the Sunday timesheets after being sidelined by more power unit problems.
"We're not in an ideal situation. There is a lot of new technology for everyone to understand, but even though we have stopped many times and spent a lot of time in the garage, each time we run the car we are learning something new," he said.
"We now have two weeks to find a lot more performance and reliability."
Mercedes-powered McLaren also hit problems, with Jenson Button halted by a high-mileage engine failure and then an electronics problem.
The delays meant the team was unable to get driver feedback on a new front wing that arrived in the morning.
(Reporting by Alan Baldwin, editing by Pritha Sarkar)