Sebastian Vettel topped the timesheets in the Red Bull RB6 on the first day of the second test in Jerez.
Poor weather conditions forced the team to begin the day on wet tyres which compromised their planned area and mechanical set-up testing.
The German, who finished second behind Jenson Button in the championship last season, completed 104 laps of the Jerez circuit, and despite a break-down in the official timing system at one point during the day, clearly set the fastest time.
Ian Morgan, Head of Race Engineering was pleased with the consistency of both car and driver, and the progress of the team, but was not particularly thrilled by the changing weather conditions. “We got a lot of laps done and the car has been good and reliable. We've made a few small changes but we didn't get through as much as the programme as we'd hoped because of the weather. Sebastian and the car were consistent on the long runs in the dry which is promising.
“We're continuing to make steady progress; the car is better than it was last week and every time we turn a wheel we seem to be moving forward a little bit.”
Vettel will test for the team again tomorrow before handing the car over to teammate Mark Webber for the final two days of the session.