Once again, some of the teams had an eye on next season, in addition to preparing for the last four races of this year.
Pace-setter Klien worked on the mechanical set-up of the F1.08, also testing various aerodynamic settings in readiness for the remaining races of 2008. The Austrian completed a total of 84 laps on his way to posting a best time of 1:19.357.
"A whole day's testing without any problems gave me the opportunity to provide the engineers with a lot of feedback on new components," said Klien. "The new surface on parts of the track provides better grip, and has smoothed out the bumps that were there before."
Robert Kubica was scheduled to take over tomorrow. However, due to an infected tooth he has had to cancel his trip to Jerez at short notice. Therefore, Nick Heidfeld is scheduled to take over testing duties for the remaining two days.
Second quickest was Monza hero Sebastian Vettel. However, unlike last Sunday, when he drove the Toro Rosso, today he was in the Red Bull, in anticipation of his switch to the Austrian outfit next season.
Set-up work was the main item on the agenda for the German youngster, as the team gets to know him and vice versa. Other work included data acquisition from a few new components. Despite losing some track time in the afternoon with a gearbox problem, Vettel completed 60 laps in total, setting the second best time of the day. Hel continues testing with Red Bull tomorrow, before switching back to Toro Rosso for the final day.
As it happens, third quickest was the Red Bull, with Sebastian Buemi at the wheel, one of several drivers under consideration for a 2009 seat.
After a delayed start, due to an unspecified mechanical problem, Buemi carried out some aero configuration work and general set-up, completing one long run at the end of the day.
According to the team, the Swiss driver made no mistakes and provided good feedback throughout the day. "I'm quite happy, it was a very good first day and I really want to thank Red Bull for the opportunity to test the car," said Buemi.
Tomorrow, driving duties will be carried out by Takuma Sato, another 2009 hopeful.
Gary Paffett was in action for McLaren, as the test team kicked off its final full session of the season. The English driver's programme included front-end aerodynamic development and set-up work for the remaining four fly-away Grands Prix.
In addition, the team started the on-track evaluation of its KERS system. The process will include a range of steps, which is initially focused on vibration and housing checks with the system in a passive mode.
Kamui Kobayashi was at the helm for Toyota, spending the day focusing on preparations for next week's Singapore Grand Prix, running in a high-downforce configuration while carrying out work on brakes and other systems. He had a trouble-free day completing nearly 94 laps. The Japanese youngster will remain at wheel tomorrow.
"We ran with the level of downforce that we expect to use in Singapore next week," said Kobayashi. "We had no major technical problems and we were able to get through our entire programme without issues. That included work on brakes and other systems and we made some good progress and collected useful data. All in all, a good day's work."
"Today we concentrated our efforts on next week's Singapore Grand Prix," added Gerd Pfeiffer, "running with a high-downforce configuration in preparation for the new night race around the city's streets. Kamui had a trouble-free day, concentrating on set-up for Singapore in the morning before completing work on brakes and software. Tomorrow we will switch our focus to prepare for the other races left on the calendar."
Brazilian Lucas di Grassi was back in action today for Renault. Conditions were warm and sunny as the French team began its final test of the season. That allowed the team to make progress with its technical programme which involved assessing some aerodynamic developments that it hopes to introduce for the final four races of the season. By the end of the day, the Brazilian had covered a total of 90 laps, finishing 1.49s off Klien's pace.
"Today we tested some new parts for the last couple of races," said di Grassi. "Everything went well and there were no problems during the day, although we had to get used to the new track surface as they have resurfaced it since the last time we were here. It's very different as they have taken out some curbs and added some curbs in other parts of the track. It was very hot in the afternoon, but it was nice to be back in the R28 and I quickly got comfortable with the car and I'm looking forward to the rest of the week."
"It's been a while since Lucas has driven the car," added Christian Silk, "so we spent some time getting him used to it once again. They have resurfaced the circuit, which has changed its characteristics a little bit for the car and the tyres and so we had to learn about that this morning. But overall I'm reasonably happy with the first day as we've done a bit of work for the races coming up and will continue with that tomorrow."
Honda continued where it left off on Tuesday, with Alex Wurz at the wheel of the RA108. The Austrian's programme for the day focused on aerodynamic and set-up evaluations. He will continue testing here tomorrow.
Williams was another team focussing on 2009 as it tried a new 2009-spec rear wing and diffuser (above). That said, the rest of the aero package on the FW30 was to 2008 regulations.
"Kazuki joined the test team today and took to the track in the FW30B interim car to continue work on the KERS and also various new components for 2009," said Sam Michael.