Sebastian Vettel topped the timesheets on the second day of testing at Barcelona, ahead of a trio of Toro Rosso hopefuls.

Unlike yesterday, however, for much of the day it was overcast, with temperatures barely reaching 14 degrees C, but that didn't prevent the 16 drivers present from completing 1277 laps of the 2.892 mile circuit.

Given that the teams are running a wide range of different aerodynamic configurations, in preparation for the 2009 rules, it doesn't mean too much, but nevertheless, Sebastian Vettel's first session as an official Red Bull Racing driver got off to a good start, as he posted today's fastest time. In fact, the top four times all came courtesy of a chassis designed by Red Bull Technology, as sister team Toro Rosso, set the next three best times.

Once Vettel was settled in, he carried on with the programme begun yesterday by Sebastien Loeb, which centred mainly on tyre data acquisition, running the softer of the two types of slick available here. Unfortunately, a brake problem meant some track time was lost in the morning, but the programme was back on schedule come the end of the day. Vettel drives again tomorrow, the final day of this test session.

For Toro Rosso, Sebastien Buemi drove all day, while Takuma Sato jumped out of the cockpit at the end of the morning, to hand over to Sebastien Bourdais.

Buemi and Sato did some long runs to gather data on the new slick tyres, with the Swiss driver having an off-track excursion on his first set of new rubber. However, he recovered well to complete another high mileage day, after yesterday's performance, which is a testament to his physical condition, given that the cars are more physically demanding to drive on slick tyres.

Sato finished his programme by doing a long stint at race pace, before handing over to Bourdais. "I have really enjoyed the test and it was great to be back in the car," said the Japanese driver. "The last test in September was a little disappointing, because I could do only 3 hours, as it rained in the afternoon. But this test has been great - I have now done my first full day's driving in 7 months and completed a total of 200 laps.

"The car has worked really well and felt great to drive," he added. "I enjoyed working with the team and it was very interesting for me to see how the engineers work. It was a great experience and chance for me and so I would like to say a big thanks to Red Bull and Mr. Mateschitz, as well as to the Scuderia Toro Rosso team."

Bourdais, no stranger to slick tyres because of his time running them in Champ Cars in the USA, believes that Bridgestone has made a step forward in tyre performance and consistency, since he tested them earlier in the year. However, it was evident that the softer of the two types of tyre had a clear advantage over the harder one.

McLaren had Gary Paffett on duty while Pedro de la Rosa helped out at Force India. Today, the Englishman switched to the KERS test car (MP4-23K) driven by the Spaniard on Monday, but his day's work was cut short at lunchtime when a minor oil leak prompted the team to effect a precautionary switch to the vacant MP4-23. The team spent the afternoon running aero and slick tyre evaluation runs. Paffett, whose best time was posted in the KERS car, will continue in the MP4-23K tomorrow.

Nick Heidfeld joined Robert Kubica for BMW as the Munich outfit once again concentrated on development work with the 2009 season in sight. Both test cars were interim cars based on the F1.08 with some aerodynamic components complying with the 2009 regulations. Kubica and Heidfeld completed 76 and 81 laps respectively, tyres and reliability being the main focus of today's work.