Toro Rosso's Sebastien Buemi picked up from where he left off in Portugal last month and set the pace today [Tuesday] as five teams kicked off a four-day test at Jerez in Spain.
Buemi, who was once again the only man running in a 2008-spec car - albeit modified - spent the day working on set-up, suspension and putting miles on the new 2009 Ferrari engine.
In addition he tested a steering system being developed for the coming season, running Bridgestone's 'soft' compound tyres initially, before switching to the intermediate and full wet tyres when rain fell around mid-morning.
He managed 104 laps in total, easily the most of anyone runner, and was more than 2 seconds up, Sebastian Vettel, who was 'best of the rest' in the new Red Bull RB5, which was unveiled to the world's press on Monday.
Vettel completed 61 tours, a vast improvement on yesterday's shakedown, which was limited to just 14 laps due to gearbox problems.
Nico Hulkenberg meanwhile came in third for Williams, around three tenths slower in the Toyota-powered FW31.
"Today Nico Hulkenberg worked on mapping, systems checks and set-ups in preparation for the first Grand Prix in Melbourne," explained Williams technical director, 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."
Heikki Kovalainen was next up and fourth for McLaren-Mercedes on a 1 minute 22.634 seconds.
The Finn ran a parallel programme, focusing on developing useful set-ups for the new car while also putting mileage on the car's active KERS device. While he had to abort a few runs due to rising temperatures, Heikki still felt the KERS device worked well.
As much of the day's work was exploratory, Kovalainen undertook most of his programme on a single set of dry tyres choosing only to switch to fresh rubber - and setting his fastest lap - towards the end of the day.
Nelson Piquet Jr was the only other runner in action and while the weather conditions did limit the team's progress somewhat, he was still able to continue the planned development programme and work on the Regie's
"It's a shame that we lost some track time today," reflected the Brazilian, "because at this stage of the season we need to get as many miles on the car as possible. As the car is so new though, 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, 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," added Renault's chief test engineer, Christian Silk.
"The forecast looks much better for the rest of the week so that should allow us to continue learning about the car."
Testing now continues on Wednesday.