Mark Webber was quickest for Red Bull Racing today [Thursday] as the final pre-season test began at Barcelona ahead F1 2010.
Webber's best effort was a 1 minute 21.487 seconds, which left him around a second up on his closest rival and with weather conditions significantly better than the previous two tests in Jerez he did just over 100 laps - despite a minor gearbox issue.
The Aussie will now hand over the Renault-powered RB6 to team-mate, Sebastian Vettel, before resuming work on the fourth and final day on Sunday.
"We had a pretty good day of testing," Webber reflected. "We did some simulations and performance items in the morning and a race simulation in the afternoon. We had a precautionary stop in the middle of the race simulation because of a gearbox oil alarm, but the guys got the car turned around pretty quickly and we finished the session, so it wasn't too bad."
"Today was always planned as a race weekend simulation day, so we did some testing along with P3 and qualifying in the morning and a race simulation in the afternoon," added Red Bull's head of race engineering, Ian Morgan.
"Everything went very well up until halfway through the race simulation, when something in the data made us decide to stop the car on track. It was nothing major though and we got the car repaired and back out until the end of the session. It went well today, apart from that small reliability issue."
Nico Hulkenberg meanwhile was second and 'best of the rest' for Williams. He did 82 tours, his quickest a 1m 22.407s.
Nico Rosberg was next up for Mercedes, one tenth slower than his fellow countryman. He spent much of the day focusing on set-up work with the MGP W01 car over longer runs alongside working on the team's race weekend procedures including qualifying and pit stop simulations. Michael Schumacher will replace Rosberg for day two.
"We had a productive day today and we were able to learn a great deal from doing so many laps," said Rosberg, who did 107 tours in total. "We're making good use of the testing time that we have and I'm feeling quite confident and comfortable in the car.
"Aerodynamically the car will change quite significantly for the first race in Bahrain so we're not focusing on the details but on general set-up work and seeing how the car behaves over long runs. Working through the race weekend procedures and pit stops is also very useful in our preparations for Bahrain."