On an overcast day Montoya would set a fastest time of 1m:16.721, completing eighty five laps. Again he was joined by test driver Marc Gene who was using an updated FW25 would finish second fastest. Juan Pablo's time was a tenth of a second faster than the time set the day before.

Juan Pablo's day would see him work on the setup of the FW26 and also tyre testing for Michelin. Marc would focus on tyre testing. Both Juan Pablo and Marc continue testing on Friday.

WilliamsF1 Chief Operations Engineer Sam Michael commented on the days testing: "The team's had another constructive session at Jerez today with Juan Pablo recording the fastest time of the test again in the FW26. With the FW26, we've concentrated on optimising mechanical and aerodynamic set up options while Marc has continued with the intensive tyre testing programme using the FW25B. The new car seems to be responding positively so we're making good progress.“

Pos Driver Team-Engine Tyres Time Laps

1. Montoya WilliamsF1 BMW (M) 1:16.721 85
2. Gene WilliamsF1 BMW (M) 1:17.197 102
3. Montagny Renault (M) 1:17.878 76
4. Trulli Renault (M) 1:17.894 132
5. Zonta Toyota (M) 1:17.974 106
6. de la Rosa McLaren-Mercedes (M) 1:18.224 63
7. Massa Ferrari (B) 1:18.409 77
8. Panis Toyota (M) 1:18.647 88
9. Badoer Ferrari (B) 1:18.684 74
10. Coulthard McLaren-Mercedes (M) 1:19.157 18