World champion Kimi Raikkonen finished the Bahrain test on top of the times after going even quicker than yesterday.
The Ferrari driver managed a best time of 1:30.455, over a tenth quicker than yesterday's time, already over two seconds faster than last year's pole position lap.
Raikkonen was joined by teammate Felipe Massa, who replaced test driver Luca Badoer in the second F2008. Massa covered 72 laps despite suffering some problems that made him lose time during the session.
The Toyota team completed their programme with Jarno Trulli and Kamui Kobayashi at the wheel of the TF108. Both men worked on set-up and development items, and Trulli was pleased after enjoying a trouble-free day.
"This was a better day for us because we had no technical problems and the weather improved quite a bit," said Trulli. "We completed a lot of laps which was important because we had quite a few things to test and we needed to get some information about the different mechanical set-ups.
"Everything went well and we are making progress but we still have to push hard to continue this improvement."
Both teams will stay in Bahrain, where another three-day session kicks off on Saturday.
Pos Driver Team Time Laps 1. Raikkonen Ferrari (B) 1:30.455 74 2. Massa Ferrari (B) 1:31.293 72 3. Trulli Toyota (B) 1:32.145 97 4. Kobayashi Toyota (B) 1:32.265 53 All Timing Unofficial