BMW Motorsport Director Dr Mario Theissen described this test by saying: "This is the most important test week of the year. After it, a seven-week ban follows." On a dry track the team would also allow Estonian Marko Asmer a further opportunity to test with the team.

The team is using this time also in preparation for the British Grand Prix in a little over a weeks time. But the team would also use this test as a time for further development of the FW25. "We've to make sure that we continue to make progress at the same speed as we did in the last few weeks. Our competitors are working hard as well," Dr Theissen added. Also present at the test was regular test driver Marc Gene. Marc would complete one hundred and five laps, with a best time of 1m:18.584. Gene would finish the day second behind Ferrari's Luca Badoer.

For Marko Asmer this was his first time time at the Barcelona circuit. The test would see the 18-year-old conduct aerodynamic tests. As such the revs of his BMW P 83 engine had been limited. He would complete ninety eight laps, setting the second slowest time but quick laps were not on the agenda for the young driver.

The team would continue on Wednesday with Ralf Schumacher taking over from Marko Asmer and joining Marc Gené.

WilliamsF1 Test Team Manager, Tim Newton commented on the days testing:
“Today was the beginning of a four-day test at the Circuit de Catalunya, our principal aim for the week being tyre development work with Michelin and general set-up comparisons of the car for the British Grand Prix.

Marc Gené and Marko Asmer performed testing duties for the team with Marc spending the day on tyre development and evaluation, completing over 100 laps, whilst Marko concentrated on aero mapping, working under a speed limitation. Marko completed 98 laps collating valuable aero data for the team.“

Pos Driver Team-Engine Tyres Time Laps

1. Badoer Ferrari (B) 1:18.200 105
2. Gene WilliamsF1 BMW (M) 1:18.584 105
3. Frentzen Sauber-Petronas (B) 1:18.791 89
4. da Matta Toyota (B) 1:19.491 79
5. de la Rosa McLaren-Mercedes (M) 1:20.308 41
6. Asmer WilliamsF1 BMW (M) 1:24.082 98
7. Wurz McLaren-Mercedes (M) no time 7