Nico Rosberg set the fastest time in the 2011-spec Mercedes W02 during the third day of testing at the Circuito de Jerez on Thursday while Lotus' Romain Grosjean set the fastest time in a 2012-spec car. Rosberg's time of 1m17.613s was 0.806 seconds faster than Grosjean's best effort, which was 0.878 seconds faster than defending double world champion Sebastian Vettel's best effort.
Crucially, however, Grosjean's Lotus E20 was the first car hit by reliability issues as it stopped in the final 15 minutes of the day after the Frenchman managed to complete 117 trouble-free laps.
Grosjean's lap tally was the third best of the day after Bruno Senna's 125 for Williams and Rosberg's 118. Vettel managed 96 trouble free laps as well.
After completing over 100 laps a day on the first two days of the test, Force India were unable to record a single lap after their French reserve driver Jules Bianchi crashed his VJM05 right at the start of the day, causing heavy damage to the right-rear side of the car. The team's mechanics were unable to repair the car in time to allow their new signing Nico Hulkenberg to do any laps.
McLaren continued its relatively low-key test with Lewis Hamilton taking over from Jenson Button and recording the fourth fastest time that was 1.851 seconds off Rosberg's best time and 1.245 seconds slower than Grosjean's best effort.
Former double world champion Fernando Alonso got his first outing of 2012 as he completed 67 laps and set the seventh best time out of the nine drivers who set a time with a lap of 1m20.412s.
1. Rosberg Mercedes 1m17.613s 118
2. Grosjean Lotus 1m18.419s +0.806 117
3. Vettel Red Bull 1m19.297s +1.684 96
4. Hamilton McLaren 1m19.464s +1.851 80
5. Vergne Toro Rosso 1m19.734s +2.121 79
6. Perez Sauber 1m19.770s +2.157 48
7. Alonso Ferrari 1m20.412s +2.799 67
8. Senna Williams 1m21.293s +3.680 125
9. Van der Garde Caterham 1m23.324s +5.711 74