De la Rosa quickest at Jerez

The Spaniard spent the day focusing on tyre work for Michelin in the V10-powered car, as teammate Kimi Raikkonen got his first experience of Mercedes-Benz's upgraded V8 engine that the team are hoping will lift them nearer the top of the field.

Raikkonen could manage no better than ninth on the timesheets, despite Juan Pablo Montoya having put in some quick times with the car earlier in the week.

Fisichella had to run a limited programme during the day while Renault tried to get to the bottom of a rear wing problem that test driver Heikki Kovalainen suffered from on Wednesday.

Fisichella and Kovalainen had to share a low mileage rear-wing throughout the day, meaning only one of them could be out on track at a time - but it did not appear to have hampered their pace.

Mark Webber gave Williams some more encouragement with the third fastest time, on the same day that rivals Honda admitted that the Cosworth engine was currently the benchmark in F1.

Webber's performance was even more encouraging considering he was using the standard gearbox that the team may revert to for the start of the season if they cannot make their quicker seamless shift system reliable enough.

Jenson Button, who ended the day fourth fastest while working on a tyre programme, was the sole Honda Racing representative as the team have already been forced to pack up their other cars in preparation for their travel to Bahrain for next week's hot weather test.

BMW-Sauber were left with more cause for optimistism about the overall pace of their F1.06 after Jacques Villeneuve set the fifth fastest time, one place ahead of teammate Nick Heidfeld.

The only blight on the team's copybook was a fuel pump failure that hit Heidfeld after lunch, bringing his testing to an end for the day.

Toyota duo Jarno Trulli and Ralf Schumacher ended the day 10th and 11th overall. The times will have left them more eager than ever to get their hands on the new aero package that will be fitted to the TF106 next week.

Vitantonio Liuzzi completed 79 laps in the Scuderia Toro Rosso STR01 as he got to grips with the new machine. The Italian stopped out on the track late in the afternoon with a mechanical problem, but the test will have provided some encouragement to the team.

Gerhard Berger, who announced earlier today that he was buying into the outfit, is due to make an appearance at Jerez tomorrow.

Midland duo Christijan Albers and Tiago Monteiro ended the day at the bottom of the timesheets as they shared the sole M16 chassis at their disposal.

Today's times:

Pos  Driver        Team                     Time      Laps
 1.  de la Rosa    McLaren-Mercedes    (M)  1:17.451   123 *
 2.  Fisichella    Renault             (M)  1:17.479    76
 3.  Webber        Williams-Cosworth   (B)  1:17.767   104
 4.  Button        Honda               (M)  1:17.990   118
 5.  Villeneuve    BMW-Sauber          (M)  1:18.179   111
 6.  Heidfeld      BMW-Sauber          (M)  1:18.278    63
 7.  Kovalainen    Renault             (M)  1:18.542    45
 8.  Rosberg       Williams-Cosworth   (B)  1:18.843    60
 9.  Raikkonen     McLaren-Mercedes    (M)  1:18.929    40
10.  Trulli        Toyota              (B)  1:19.083   103
11.  R.Schumacher  Toyota              (B)  1:19.320   107
12.  Liuzzi        Toro Rosso-Cosworth (M)  1:19.394    79
13.  Albers        MF1-Toyota          (B)  1:20.685    90
14.  Monteiro      MF1-Toyota          (B)  1:20.922    63

* Hybrid car (restricted V10)