Jenson Button gave himself and his BAR team the perfect boost today, by breaking the unofficial lap record at the Circuit de Catalunya. To put the icing on the cake, on a day in which the team completed over 261 laps of the Spanish track, teammate Takuma Sato was third quickest, albeit 0.695s off the pace.

The Englishman, running the aero package that the Brackley outfit is expecting to run at Imola, had a trouble-free day, giving the under-fire team a much-needed fillip before the start of the European season. Jenson spent the morning continuing his aerodynamic evaluation, alongside a suspension test. In the afternoon he concentrated on fine-tuning the car alongside some chassis set-up work.

Later in the day, once Sato had finished his programme of tyre evaluation with a series of longer runs, and therefore not breaking the agreement whereby teams only run two drivers, Enrique Bernoldi ran a number of shakedown laps.

Second quickest was Bahrain runner-up Jarno Trulli, as Toyota continued to impress. Ricardo Zonta was also on duty for the Japanese outfit, however the new aero package, which was due to be tried today, didn't materialise, according to reports it isn't ready yet.

McLaren had Kimi Raikkonen and Alexander Wurz on duty, the Austrian back in the MP4-19B. The former Le Mans winner matched yesterday's best time - posted by teammate Pedro de la Rosa - to one thousandth of a second, while Kimi, in the MP4-20, was ninth quickest, 1.37s off the pace.

The Finn's programme ended at approx. 16:30 with a slipping clutch. It is hopes that the test team will fix the car overnight so that he is able to complete his testing programme tomorrow.

Alex was also undertaking tyre testing for the Spanish Grand Prix today. In the morning he completed a series of short runs, but lost an hour in the afternoon after the car developed a hydraulic leak.

"This morning I completed my planned programme, and as well as testing the option Michelin tyre for Spain continued the set up development work which Pedro started yesterday," said Raikkonen. "I am looking forward to the final day of testing tomorrow," added his teammate.

Ferrari had Rubens Barrichello and Luca Badoer on duty, the Brazilian finishing fifth quickest, the Italian seventh.

Rubens gave the F2005 its debut at Barcelona as he worked on Bridgestone tyre development and on fine-tuning the set-up of the car. Luca continued the Bridgestone tyre development programme previously carried out on Tuesday and Wednesday by Marc Gene.

On Friday, Badoer is joined by Michael Schumacher.

It was a tough day at the office for Alonso and Fisichella (again). The Spaniard suffered an engine failure while Giancarlo had an accident early in the afternoon at Turn 3 from which he escaped unharmed.

As the French outfit concluded this week's testing, chief test engineer Christian Silk commented: "Overall, we have completed a very successful week's work in Barcelona. The team made a big effort to bring our programme forward, and we have had three dry, productive days' running.