Having completed a 14 lap shakedown yesterday, today Red Bull was joined by McLaren, Renault, Williams and Toro Rosso as the second round of pre-season testing got underway at Jerez.

Once again, Toro Rosso was using the 2008 car, consequently, once again, it was Sebastien Buemi who set the pace. In what should be the STR3's final test session, Buemi worked on set-up, suspension and on putting miles on the 2009-spec Ferrari engine. In addition, the Swiss driver tested a steering system being developed for the coming season.

Buemi began the day on "soft" compound tyres, but mid-morning rain meant he also got the opportunity to gain further experience on the intermediate and full wet tyres.

Second quickest, and therefore the pace-setter in terms of 2009 cars, was Sebastian Vettel in the brand new RB5. . The day went well for the Austrian outfit with successful runs in dry conditions until the mid-morning rain left the track wet until well into the afternoon, consequently the car spent quite a bit of time in the garage.

Vettel is due to do the bulk of the driving over the course of the four days, but tomorrow morning Mark Webber will get his first taste of the RB5, not just to assess the car's potential, but also to see how he feels physically in the cockpit as he continues his recovery after breaking his leg in November.

Nico Hulkenberg was back on duty for Williams, the German driver completing 82 laps and finishing just 0.266s off Vettel's pace.

"Nico worked on mapping, systems checks and set-ups on the FW31 in preparation for Melbourne," said Sam Michael. "Although there was some wet weather in the middle of the day, there was plenty of dry running and we have a lot of useful data to look at tonight."

For McLaren, Heikki Kovalainen, who is on duty for all four days of the test, ran a parallel programme, focusing on developing useful set-ups for the new car while also putting mileage on the KERS device.

The Woking team set itself prudent targets on both thermal and pressure thresholds in order to safeguard the machinery and this resulted in a few aborted runs when those thresholds were reached. The Finn felt the KERS device worked well but required further work in concert with the car's set-up to produce optimum results.

As much of the day's work was exploratory, the team chose to undertake most of its work on a single set of dry tyres choosing only to switch to fresh rubber - and set its fastest lap - towards the end of the day.

The team will continue with the same programme tomorrow and is optimistic of increasing the length of the runs as it increases its understanding of the KERS device.

Nelson Piquet was behind the wheel of the R29 as he continued Renault's development programme and despite the rain showers, the French team was able to work on the on-track development of its KERS system, which will continue throughout the week.

Better conditions are forecast for tomorrow when the Brazilian will remain in the car for a second day of work. He will then hand the R29 over to Fernando Alonso for Thursday and Friday.

"It's a shame that we lost some track time today because at this stage of the season we need to get as many miles on the car as possible," said Piquet. "As the car is so new, we learn something with every lap and we have some useful data to go through this evening. The forecast looks better for tomorrow so hopefully we can continue the work we started today."

"The track was inconsistent today because of the weather," admitted Christian Silk, "but it dried out by the end of the day and we put a couple of long runs together and the car behaved well and gave us some good data. The forecast looks much better for the rest of the week so that should allow us to continue learning about the car."

Today's Times - All Times Unofficial