It was a case of as you were on the final day of the first winter test of the 2008/09 Formula 1 'off' season around Barcelona's Circuit de Catalunya, with Red Bull Racing and Scuderia Toro Rosso machines monopolising the top of the timesheets - and drivers whose name begins with the letters 'Seb' tending to perform rather well.

Sebastian Vettel picked up from where he had left off on day two, shaving almost a further half second off his best time aboard Red Bull's RB4 to lead the way and send out a warning signal that in 2009 he fully intends to add to his Italian Grand Prix success achieved with STR. The young German worked on a programme centred upon the evaluation of Bridgestone's new slick rubber, and ran with similar levels of downforce to those that can be expected next year.

"It was good to be back in a race car again, for the first time since Brazil," the 21-year-old stated. "Running the 2009 slick tyres was very interesting, and very different to what Formula 1 has been used to for the past few years.

"It was also a useful couple of days for me from the point-of-view of getting to know the engineers and the rest of the team. It is important to develop a common understanding between us - and winter testing is the ideal opportunity to do just that."

"This was a successful three days for us," concurred the Milton Keynes-based concern's chief test engineer Ian Morgan, "and we completed all the high-priority items on our job list.

"As for Sebastian, he settled in very quickly and it actually felt as though he'd been with us for a long time already, which is a good sign! We now have plenty of data, particularly on the tyre front, which we will put to good use at the next test session, at the Jerez track next month."

Right behind Vettel, as on Tuesday, were the cars of the team he has recently departed, Scuderia Toro Rosso. With Takuma Sato having completed his running on day two, however, only 2008 incumbent S?bastien Bourdais and GP2 Series star S?bastien Buemi remained, both giving a good account of themselves as they potentially battle it out for a seat at the small Faenza-based squad next year.

Bourdais was the quicker of the two namesakes by just over three tenths of a second, and though neither was able to get within half a second of Vettel, it was nevertheless another productive day's work, affirmed the Red Bull 'junior' outfit's chief engineer Laurent Mekies.

"There was a two-fold purpose to these three days," the Frenchman explained, "firstly evaluating drivers for next year and secondly assessing the 2009 Bridgestone slick tyres, while running with the level of downforce we expect to have next season.

"The high number of laps completed means we have been able to carry out both these tasks to our satisfaction. On the tyre front, we tried a variety of suspension and mechanical set-up options, which means we have plenty of data to analyse, in preparation for our next test at the Jerez circuit in mid-December."

Whilst Bourdais is fighting to retain his drive in the top flight beyond just his rookie campaign in 2008 - one that improved significantly as the season wore on - Buemi is bidding to launch his F1 career, following a year spent testing for Red Bull and two in the GP2 feeder category.

"It's been a useful one-and-a-half days, trying various set-up options to find the right direction for next year's car," remarked Bourdais. "Of course, the 2008 car was not designed to run on the '09 slick tyres, which means you don't always have the necessary range of adjustment to exploit them fully, but it was an interesting experience nevertheless."

"Another positive day to round off this test session," added Buemi. "I'm really happy with how testing went overall; the team did a good job and I think I did too, which could be important for my future!"

Fourth on the final timing screens - albeit a second adrift of the two Toro Rossos and almost two seconds shy of Vettel - was McLaren-Mercedes test driver Gary Paffett. The former DTM Champion reported no issues aboard the KERS-equipped MP4-23K, and made good progress in terms of understanding the slick tyres and new aerodynamic configurations, as well as KERS' impact on car dynamics.

Fifth-fastest was Honda's Jenson Button, the Englishman less than three tenths of a second ahead of the impressive Bruno Senna in the second RA108, with the pair - possible team-mates in F1 next year - sandwiching the evenly-matched BMW-Sauber duo of tester Klien and regular race driver Nick Heidfeld. Senna lapped almost three seconds quicker than he had done on the opening day, and seven tenths up on the best effort set by fellow GP2 graduate Lucas di Grassi - his principal rival for a seat at the Brackley-based outfit in 2009 - on day two.

"It's nice to be back in a car that I enjoy driving," enthused Button, who continued his set-up programme, running on slick rubber and working through a series of aerodynamic and suspension evaluations on the modified RA108. "Taking a lot of the downforce off and running on slick tyres suits my driving style a lot more than grooved tyres.

"I've had a fun couple of days and it's been very useful, as we have tested many things which should help us with the new car. It's been a positive start to 2009 already, and I'm very pleased. I've just got to keep pushing the team hard now to get the improvements that we are hoping to achieve for next year."

"Today has been a really good day and I'm very pleased," added Senna, who clearly enjoyed his first full day of F1 action - even if he was frustrated by traffic in the morning. "I've become a lot more comfortable and confident in the car and I think that showed in the lap time, both in the actual time and also the consistency.

"We found some good set-ups and we were able to make a lot of progress through the day. Whether what I did today is good enough is for the team to decide now and I respect that, but for me personally, for my first time in a Formula 1 car, I have to be happy with what I achieved today.

"Driving a Formula 1 car is a very special feeling, and it is very easy to know why it is the pinnacle of motorsport. It's very different to anything else you can drive, and I just wanted to go faster and faster.

"Aside from the hard work and focus here this week I have really enjoyed myself. The Honda team are very professional, and I am proud to have spent the time with them during this very special week for me."

"The first test of the winter in Barcelona has seen us commence our on-track preparations for 2009, a season which will see the most significant change in Formula 1's technical regulations for many years," summarised the Japanese concern's team principal Ross Brawn. "We have been running two modified RA108 chassis', with an aerodynamic package representative of the downforce levels required for next season.

"We have also conducted an intensive tyre programme with the Bridgestone Potenza slick tyres. Having been sensible in the use of our tyre allocation so far this year, we are in the best possible position to gain information about the new slicks ahead of the launch of our new car. Whilst the temperatures have been quite cool this week, which has affected the behaviour of the tyres, both the team and drivers are happy to see Formula 1 back on slicks.

"In addition to our main test programme, we took the opportunity to evaluate the emerging talents of Lucas di Grassi and Bruno Senna. Both drivers spent one-and-a-half days in our car, which has enabled the team to assess their performance and level of technical skill.

"Lucas and Bruno have both performed admirably over the course of the week, and their evident enthusiasm and commitment has made them a pleasure to work with. We will now take some time to carefully consider our findings from this test before reaching any further conclusions."

At BMW, meanwhile, both drivers again focussed on evaluation work with the interim F1.08B - based on a 2008 chassis with some aerodynamic components complying with the 2009 regulations - and completed 88 (Heidfeld) and 106 laps (Klien) respectively.

The Austrian was once more behind the wheel of the car equipped with BMW's own KERS system, but just before the end of the morning session he endured a minor 'off' caused by a hydraulic-related problem in the drivetrain. Following repairs the 25-year-old was able to resume testing duties after the lunch break.

"Definitely the slick tyres provide more grip than the 2008 grooved tyres," underlined Heidfeld, who for his part concentrated on reliability, mechanical and aerodynamic set-up options and collecting data on the all-new power-adjustable front wing. "On the other hand we have to start from zero by learning how the slick tyres heat up and for how many laps they deliver optimum performance."

Nelsinho Piquet wound up ninth in the order for Renault, the Brazilian having run on every day of the test and again looking at slick tyre evaluation and R&D work with an R28 set up to simulate 2009 regulations. A trouble-free day enabled the 23-year-old to complete 94 laps for the former world champions without any drama.

"We had a busy morning," he confirmed, "continuing with the work we began earlier this week by evaluating the tyres and looking at some more development parts in preparation for next year. The car still feels strange running with settings to simulate 2009, but we now have lots of data to work through and so it has been a valuable few days for the team."

"It's been a good test for us," agreed the R?gie's chief test engineer Christian Silk, "and we were able to cover the main test items that we had scheduled, which included a few R&D items that gave us some positive results. Working with the car on slick tyres has been very useful, and the engineers now have some valuable data to take back to the factory and to look at before the next test in a couple of weeks' time."

Williams' test driver Nico H?lkenberg placed tenth, four tenths of a second ahead of Ferrari counterpart and former grand prix ace Luca Badoer, who covered 120 laps as he concluded the Scuderia's engine and gearbox reliability programme begun on Monday, as well as looking at the development of new components aimed for 2009 introduction.

The final two drivers on the list at the end of the day were Giancarlo Fisichella and Pedro de la Rosa, both out for Force India and completing 93 and 88 laps respectively as they were separated by a scant 17 hundredths of a second.

To see the testing times in full, click here