Rubens Barrichello topped the timesheets on the final day of testing at Jerez, the Williams driver posting the fastest time of the four day test.

After three days of sunshine, conditions were somewhat different today with blustery winds throughout, heavy cloud for much of the afternoon and heavy rain for the final fifteen minutes.

Having lost time over the last couple of days, mainly through KERS related problems, Williams had an altogether better time today, with Barrichello completing 103 laps, mostly consisting of long runs. There was one stoppage around midday due to a hydraulic leak but overall the Grove outfit declared itself satisfied with the progress made.

"Nothing was going to stop us from doing over 100 laps today!" said Sam Michael. "After limited running up to now, we concentrated on setup and long runs. Rubens was trying various things to learn about the Pirelli tyres - some worked, some didn't. Now we've also gathered some data on the Pirelli wet tyre after a small shower at the end of the session. At the next test we will also have KERS back on the car as we ran without it today."

"We did suffer from a hydraulic leak during the middle of the day," he continued, "but overall it's encouraging that we've had no major fundamental failures on the car - especially considering how tight the package is. All of the faults that have been causing our downtime in the recent days are small things that systems will quickly put right."

"We completed some long runs today," added Barrichello, "and looked at trying some different things on the car. This morning was also the first time we could run a few new sets of tyres and get some momentum. The car performed as it should do so I am happy with that. The day went with minor problems, but we have some good direction and it is great to get some more mileage on the car."

Kamui Kobayashi continued for Sauber, and while the Swiss outfit lost some track time in the afternoon due to a power train related issue, it remains positive about the lessons learnt in Southern Spain.

"Today we had to stop early because of a power train related problem," revealed head of track engineering, Giampaolo Dall'Ara, "but still we have covered a reasonable mileage. We started in the morning with runs of about eight laps each on the hard Pirelli tyre compound to test mechanical set-up options. After 11:00 we did one single run on super soft tyres, and then worked again on the car's set-up on harder tyres.

"After lunch we did long runs with medium and hard tyres, the longest distance being 18 laps. Kamui also had an off today and got stuck in gravel, but without damaging the car. Because we had to finish early we had no running in the wet at the end.

"Overall we had very good track conditions in Jerez and did a lot of tyre evaluation, worked on systems and set-up. While it was also good for Kamui to work with the new systems, it was even more important and a really positive experience for the team to do some proper work with our new driver, Sergio, here in Jerez. More mileage in total would have been appreciated, but there are more tests to come."

"For me these two days have been very interesting," said Kobayashi. "Although we lost track time today, we still covered some good mileage and I have learnt a lot more about the character of the new tyres. We still have to work hard but to me it was a positive test."