Further down the order, Italian GP winner and yesterday's pace setter Sebastian Vettel was fourth, having reverted back to the Toro Rosso fold.

The German did 93 laps and was almost half a second up on Sebastien Buemi, who was fifth for Red Bull's 'A' team in the Renault-powered RB4.

Vettel had a busy programme to work through and most of it centred on aerodynamics and set-ups. He also evaluated some suspension and power steering options, as well as testing aimed at 2009 car systems.

"At this, the final session of the season, our main test topics were trying out some new components on the car and the evaluation of two drivers, Sebastien Buemi and Takuma Sato," said Toro Rosso team boss Franz Tost. "On Wednesday, Red Bull young driver Buemi was in the cockpit and, as expected, he did a good job.

"On Thursday, Japan's Takuma Sato was behind the wheel. Unfortunately, he was only able to run in the morning because the rain arrived at lunchtime. Despite only completing a few laps, Sato also put up a good performance.

"Although those two days were something of an audition for a 2009 seat with Scuderia Toro Rosso, Red Bull is in no hurry to make a decision at this point in the year, when we are concentrating on doing well in the final four races."

"Definitely the best of the three days," added Red Bull Racing's chief test engineer, Ian Morgan. "Basically, Seb [Buemi] hardly got out of the car and every time he came into the pits, we put something new on for him to try. Hopefully, the race team can see the results in the coming flyaway races."

Of the rest Timo Glock came in sixth for Toyota and he had no problems, competing 110 tours - the most of anyone runner. The German concentrated on aero comparisons for the coming races including Singapore and Japan as well as work on brakes and other systems.

"That was a hectic day of testing because I carried out a lot of work for the different kinds of racetracks we have coming up," he recounted. "We got through a lot of laps, finishing our programme without issues. It's good that we had consistent weather today but it was still a bit tricky because yesterday's rain on this new surface meant that there was only one line and the rest was really dirty. Nevertheless we made useful progress and gathered information that will help us in the final part of the season."

"Following yesterday's interruptions, today we had a much busier day of running," added Toyota's test team manager, Gerd Pfeiffer. "Timo's programme included work on aerodynamics for the coming races along with brakes and other systems. We had no technical problems and we collected a lot of useful data.