By: Max Davies, F1 correspondent
Mercedes GP driver Nico Rosberg set the fastest lap on the third day of Formula One pre-season testing at the Circuit de Catalunya, Spain.
The German's best time of 1m23.789s was set towards the end of the day after light rain and a wet track this morning prevented any dry running until just before the lunch break.
Set on a low-fuel run, the Mercedes MGP-02 seemed more stable around the Spanish circuit - which is renowned for being able to highlight any aero or stability deficiencies in a chassis - than it had appeared in the first two winter tests at Valencia and Jerez.
"For sure we still have some problems, but it's going in the right direction," Rosberg said. "Today we learned a lot and made some progress, so things are improving.
"It was expected that we would be struggling in the winter because the car is built mainly to test reliability and it's not there for performance," he said. "The performance is going to come in the next few weeks and then we have to wait and see where we are," he added.
Rain showers greeted the drivers at the start of the day's running. But combined with low temperatures and high humidity, the circuit failed to provide an opportunity for slick tyre running. Conditions were still treacherous and managed to catch a number of drivers out - the day's proceedings were halted by several red flags. Lap times were around five seconds off the dry times seen yesterday.
The afternoon provided the drivers with a few off-line damp patches and soon the lap times began to fall with Vitaly Petrov ending the day in second for Lotus Renault on a 1m23.463s. Accumulating 93 laps, the Russian spent most of the morning in the garage but a busy programme in the afternoon saw his set his best time, like Rosberg, on a series of short-lap runs late in the day.
There was no sign of a break for McLaren from the reliability woes that have blighted their testing schedules this winter as Lewis Hamilton was forced into the garage repeatedly after having to abandon planned stints in the MP4-26.
Eventually, the car was sorted and the 2008 world champion was able to set a fast pace on the drying track before ending the day in third place with a total of 93 laps and a best time of 1m23.858.
"This was a positive day: we've been focusing on our programme, trying to complete as many laps as possible, improve reliability and understand the Pirelli tyres," Hamilton said. "We're learning more and more about them every day.
"We've had a few technical issues with this car, but the guys have been working incredibly to rectify them. To get more than 90 laps under my belt today was a big positive, and I'm looking forward to a trouble-free day tomorrow."
Pastor Maldonado took fourth for Williams with a 1m24.815s and a total of 60 laps although the Venezuelan lost some time with an alternator problem. "It was a good day for us overall," he confirmed. "This morning it was wet and we lost some time as I spun the car trying to judge the track conditions when it was quite slippery. Everything is running well and I am happy as I feel we have improved the car from Jerez.
Mark Webber's best of 1m24.995s was only enough for fifth quickest on a day when the Red Bull Renault driver completed a total of 139 laps and that included a full race distance of 66 laps. The Aussie was also one of the causes of a red flag - his RB7 stopping out on the track with only a few minutes remaining and thus bringing the day's proceedings to a premature end.
"Today went well, with nearly 140 laps completed, and you can't complain about that," said Webber. "Obviously, we now have a lot of data to digest and we're learning a huge amount about this car and how to get the best from it. It was damp all morning and that meant we had a pretty condensed programme this afternoon but we got through it well and, I have to say, the car ran really, really well. A good day and we'll come back tomorrow to learn some more."
Jarno Trulli declared himself happy with the day's running for the Team Lotus programme. Despite more water leaks hampering the quest for mileage, the Italian claimed sixth fastest on a 1m25.454 despite amassing only 48 laps in the T128.
"Despite some mechanical gremlins which cut short my running time today we managed to collect some good data and overall I have a good feeling about the car," Trulli confirmed.
"It's good to see that without doing many miles, and it being my first day in the car today on the new tyres in Barcelona, I managed to do some consistently good lap times throughout the end of the afternoon session. Tomorrow we want to carry out more setup evaluation as today I didn't run that much and didn't get the chance to explore the car as I would have liked."
Sergio Perez was seventh for Sauber-Ferrari with a 1m25.557s after spinning and causing a temporary red flag while Force India's Adrian Sutil took eight with a 1m25.720s effort.
Sharing the Toro Rosso programme, Sebastien Buemi and Daniel Ricciardo ended the day in ninth and thirteenth positions with 1m26.155s and 1m28.329s respectively.
Ricciardo was arguably the most impressive driver in the morning running - the Australian youngster setting a quick pace on slick tyres on the damp circuit before handing over to Buemi in the afternoon. Ricciardo's time was all the more impressive as Hamilton's best was marginally faster and set later in the day when the track surface was drier.
Ferrari collected more data as Filipe Massa recorded 123 laps and a best time of 1m26.508s to claim tenth place and causing two red flag stoppages. Timo Glock's best lap of 1m26.598s was set on what proceed to be a productive day for Virgin Racing with the German completing 97 laps in the MVR-02.
Narain Karthikeyan ended the day last - his 1m30.722s lap not really representative as the Indian drove the morning session before handing over to Giorgio Mondini. The former Midland F1 test driver marked his return to the sport by recording a 1m28.178s lap.