Dell blames these added delays on continued testing of driver compatibility, along with continued site kinks, but they do claim to have eligibility problems ironed out, so at least that's a start.

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The nearest challenger to the Red Bull drivers was Mercedes' Nico Rosberg, who continued to show the pace which saw him go faster than any other driver during preseason testing.

CNN: Vettel off to a flier as Red Bull set the pace in Melbourne

Brawn has been impressed with Hamilton during preseason testing, despite a hydraulic problem causing the British driver to crash out of his first drive for the team at Jerez.

CNN: Brawn defiant amid talk of change at Mercedes

But a rule change, announced on Friday, will allow one day of testing at a non-F1 circuit if the substitute driver has not raced in F1 for two seasons.

BBC: F1 amends in-season testing rule after Schumacher row

Hamilton won last year's title by a single point from Brazilian Ferrari driver Felipe Massa, who has already had a day testing his team's new car.

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The research vehicle is a testing platform aimed at the development of systems capable of enhancing the driver's perception of his or her environment, assisting in the decision-making process and improving overall driving skills.

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"Winter testing is more crucial now than in any other season before, " warned Toyota driver Jarno Trulli, who completed just 30 laps in Tuesday's rain-hit session.

BBC: F1 teams face testing times