Toro Rosso 2009 hopeful Sebastien Buemi continued to set the pace at Jerez today, topping the timesheets as he did yesterday and all of last last week.

Sebastian Vettel took over from Brendon Hartley in the second Red Bull car as the Milton Keynes-based outfit concentrated on making set up changes to improve the balance of the car on the new-for-2009 slick tyres.

Although Vettel ran wide at Turn One a couple of times, there were no significant problems and both drivers completed 83 laps apiece.

"It's been a very good test so far," said Buemi, "we've been improving with every lap, which is really good for next season and I'm happy. We're learning more about the slick tyres too, which is important. I'm looking forward to tomorrow and trying to improve myself more."

Robert Kubica joined Nick Heidfeld as BMW continued with its two F1.08B interim cars, based on the 2008 chassis with some 2009-spec bodywork. While Heidfeld used a conventional car, Kubica continued the development work with BMW's own KERS device.

Both drivers started their test programmes nearly two hours late this morning due to the cold morning temperatures. However, after the sun had heated up the track, both drivers worked on the set-up of their respective cars.

The main goal again was collecting data, so while the Pole concentrated on energy strategies using the KERS system, his German teammate evaluated different solutions for the mechanical set-up of the car, while the team collected more information on the new slick tyres.

"After the delay in the morning the weather was nearly perfect, so overall it was a good day for me", said Heidfeld. "I did short as well as long runs to compare tyre wear. At the end of the session I did some race start simulations, as this is also an area where we have to adjust to the slick tyres."

For Williams, Kazuki Nakajima took over from Nico Hulkenberg, the Japanese driver continuing with tyre testing and general set-up work.

"We lost a small amount of track time this morning due to the icy weather," said Dickie Stanford, "but the car has been running well and we've had no other problems. Kazuki will continue in the car tomorrow for our last day of testing this year."

Tomorrow is the final day of testing here as all three teams conclude their 2008 programmes.