The days testing was run under sunny conditions. All three drivers tested with the 2003 FW25 running with 2004 components, such as a new gearbox.

By the end of the day it would be Juan Pablo Montoya who would be leading the times, followed by Ralf and Marc. Juan Pablo would seta  time of Colombian 1m:10.081, focussing on tyre evaluation tests for Michelin. This was the fastest lap time ever achieved at the Spanish circuit. The FW25 was running with the 2004 P84 engine. Juan Pablo would complete sixty nine laps.

For Ralf Schumacher his day would be spent working on suspension setups. He would finish second with a time of 1m:10.718. Test driver Marc Gene was third ahead of McLaren's  Alex Wurz. Marc would complete fifty seven laps with a best time of 1m:11.224.

WilliamsF1 Test Team Manager Tim Newton commented on the days testing by saying: "The day started relatively slowly but soon picked up by mid-morning. The team spent the session testing chassis set-ups and evaluating tyre compounds with Michelin. We also successfully ran our new gearbox. By the end of the session, our drivers had recorded the fastest times of the field and completed a total of 163 laps."

BMW Motorsport Director Mario Theissen had previously commented on the up-and-coming periods of testing by saying: "The BMW P84 engine has already passed its first successful tests, WilliamsF1 has announced an innovative chassis and the integration of the factories in Munich and Grove is progressing."

For the BMW WilliamsF1 Team these tests will be crucial in light of the changes that are taking place in the 2004 season reliability and durability will be crucial in determining a good result. In 2004 the P84 engine will have to 800 kilometres, as one single engine will have to be used for all sessions of a GP weekend.

Pos Driver Team-Engine Time Laps

1. Montoya Williams-BMW (M) 1:10.081 69
2. R. Schumacher Williams-BMW (M) 1:10.718 37
3. Gene Williams-BMW (M) 1:11.224 57
4. Wurz McLaren-Mercedes (M) 1:11.299 53
5. Montagny Renault (M) 1:11.823 84
6. Webber Jaguar-Cosworth (M) 1:11.876 37
7. Trulli Renault (M) 1:11.950 89
8. Klien Jaguar-Cosworth (M) 1:11.955 84
9. Coulthard McLaren-Mercedes (M) 1:12.035 47
10. Bell Jaguar-Cosworth (M) 1:12.330 63
11. Briscoe Toyota (M) 1:12.660 71