Nakajima on top at Barcelona
Williams rookie Kazuki Nakajima was the surprise pacesetter on the final day of testing at Barcelona's Circuit de Catalunya.
With teams finally able to get some dry running after two days of rain, the Japanese driver clocked a best time of one minute 22.153 seconds during the afternoon session.
It was a successful end to a tricky test for Nakajima, who had yet to drive a F1 car in the wet.
"Initially it was a bit of a difficult test because of the weather but it was good for me to get some experience in wet conditions," he said.
"The car is feeling good, but we couldn't do as much work with it as we wanted to because of the bad weather.
"It was still a good week for us though overall."
Despite stopping twice on the track, McLaren-Mercedes newcomer Heikki Kovalianen was second quickest, just 0.050s off the pace, with test driver Pedro de la Rosa a further 0.023s back.
Felipe Massa set the fourth best time; however, it was not a true reflection of the Ferrari F2008's pace as the Brazilian did have the edge over his rivals in long-distance runs.
And, it was during one such longer stint that Massa brought out one of seven red flags after spinning off the track.
Nico Rosberg posted the fifth best time, just 0.093s slower than team-mate Nakajima.
"We've had plenty of running in the wet this week and we looked pretty good, which was positive," the Williams driver said.
"It wasn't that easy to drive in the conditions, it's hard to keep the tyres in the working window, especially without traction control, so you're always quite on the limit.
"The last day was dry and so we managed to cover a lot of laps with no problems at all.
"Over the three days, we got some important reliability issues sorted out. We seem to be progressing well with the new car and I am happy with the improvements we're making."
Mark Webber was a further 0.229s back although the Red Bull driver had a problematic day, stopping twice out on track.
David Coulthard and Luca Badoer completed the top eight ahead of Fernando Alonso, who joined the list of those bringing the session to a temporary halt when his Renault R28 broke down.
"We have been waiting for a long time to do some dry running and we made the most of it," Alonso said.
"The track conditions were not perfect, but they were good enough for what we wanted to test and they remained consistent for the whole day.
"We tested some small things with the car and I was happy with the performance and behaviour of the car.
"Now I'm looking forward to next week for our last three days here in Barcelona."
1 K. Nakajima Williams 01:22.153 32 laps
2 H. Kovalainen McLaren 01:22.185 64 laps
3 P. de la Rosa McLaren 01:22.208 92 laps
4 F. Massa Ferrari 01:22.213 95 laps
5 N. Rosberg Williams 01:22.248 108 laps
6 M. Webber Red Bull 01:22.477 81 laps
7 D. Coulthard Red Bull 01:22.499 102 laps
8 L. Badoer Ferrari 01:22.535 102 laps
9 F. Alonso Renault 01:22.657 61 laps
10 T. Glock Toyota 01:22.901 109 laps
11 N. Piquet Jr. Renault 01:23.286 104 laps
12 K. Kobayashi Toyota 01:24.132 56 laps
13 N. Hulkenberg Williams 01:24.222 59 laps