Christian Klien posted the quickest time on the second day of Formula One testing at Jerez as BMW Sauber continued to lead the way in Spain.

The Austrian took over at the wheel of the lone F1.08 from Marko Asmer and spent the day working on mechanical set-up of the car, while also testing a number of aerodynamic settings focused on the remaining events on the 2008 calendar.

Klien completed 84 laps during the course of the day and posted a best time of 1min 19.537secs, which put him three tenths of a second clear of his nearest rival.

"A whole day's testing without any problems gave me the opportunity to provide the engineers with a lot of feedback on new components," he said. "The new surface on parts of the track provides better grip, and has smoothed out the bumps that were there before."

Klien was due to hand the car over to Robert Kubica for the third day, but with the Pole suffering from an infected tooth, Nick Heidfeld will instead take over at the wheel.

Klien was followed on the timesheets by Sebastian Vettel who, fresh from his maiden F1 win at the weekend in Monza, was called up by the senior Red Bull team to complete a day of testing in the RB4.

The young German completed 60 laps over the course of the day with a best time of 1min 19.878secs as he acclimatised himself with the team he will join for 2009. Although some time was lost with a gearbox issue, he was able to complete valuable set-up work and will continue at the wheel tomorrow.

Vettel was four tenths of a second clear of Sebastien Buemi as the GP2 regular as given his opportunity to test with Toro Rosso. Buemi was one of the busier drivers on track as he completed nearly 90 laps, despite the start of his 'audition' for a 2009 race seat being delayed by a mechanical issue early in the morning.

The Swiss driver completed aero configuration and general set-up work in the STR3 and will now hand the car to Takuma Sato tomorrow as the Japanese driver makes his return to F1 for the first time since the collapse of the Super Aguri team earlier in the year.

"I'm quite happy," Buemi said. "It was a very good first day and I really want to thank Red Bull for the opportunity to test the car."

On a day when only two F1 regulars hit the track, McLaren entrusted the lone MP4-23 to test driver Gary Paffett as the team started the ontrack evaluation of its KERS system ahead of 2009. The initial focus of the KERS testing was on vibration and system checks with the system in a passive mode.

The DTM ace also worked on preparation for the final four flyaway events of the season with his work focused on front-end aerodynamic development and set-up work.

Toyota were the busiest team in action with Kamui Kobayashi completing nearly 100 laps as the Cologne-based squad kicked off three days of running. The Japanese driver ran in a high downforce configuration as he worked through a programme focused on the first ever F1 night race in Singapore while also working on brakes and system checks.

His best time of 1min 20.759secs was little more than a second off the pace set by Klien.

"Today we ran with the level of downforce that we expect to use in Singapore next week," he said. "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."

Another man with plenty of GP2 experience was in action for Renault, as Lucas di Grassi kicked off three days of running with the F1 team in his role as test driver.

He made good progress with a technical programme which involved assessing some aerodynamic developments that the team hopes to introduce for the final four races of the season and he was pleased to get valuable mileage under his belt at the wheel of the F1 car.

"Today we tested some new parts for the last couple of races," he said. "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."

Alex Wurz was seventh quickest for Honda, while the eight runners on track were completed by Kazuki Nakajima, with the Williams driver taking over at the wheel from F3 Euroseries regular Dani Clos.

Neither Ferrari or Force India were in action.