Ferrari driver Sebastian Vettel set the pace on Day One of the two-day Barcelona test, a day where Williams ran a radical rear wing and Renault trialed an upgraded engine.
Vettel, who arrived at the track on Tuesday morning with Ferrari saying their focus will be on tyres, clocked a 1:23.334 in the hour after lunch.
Using the soft tyres at roughly the same time and in the same conditions as he had in qualifying for the Spanish GP, he shaved a tenth off his time to post a 1:23.220.
That put him 0.117 seconds up on Mercedes’ Nico Rosberg, who had briefly led the way after lunch before Vettel’s time eclipsed his.
Jenson Button, who had led the way at the lunch break, dropped to third as he did not improve on the 1:23.753 that he had set in the morning on the super-soft rubber.
Romain Grosjean was fourth quickest as he put a new chassis to the test. The Frenchman announced ahead of the Spanish test that Haas would change his chassis ahead of Tuesday’s running as he has been “struggling since China with something we don’t quite yet understand.”
His best time, a 1:23.882, was 0.662s slower than Vettel’s pace-setting lap.
Pascal Wehrlein had a great day out with Manor as he was fifth quickest ahead of Daniel Ricciardo. The Red Bull, who finished fourth at Sunday’s Spanish GP, put Renault’s latest engine upgrade through its paces on Tuesday.
Toro Rosso test driver Pierre Gasly was seventh ahead of Alfonso Celis, who put in a late run to clock a 1:25.467, Alex Lynn and Esteban Ocon, who was in action for Renault.
1 S. Vettel Ferrari 1:23.220 103 laps
2 N. Rosberg Mercedes 1:23.337 +0.117 116 laps
3 J. Button McLaren 1:23.753 +0.533 86 laps
4 R. Grosjean Haas 1:23.882 +0.622 96 laps
5 P. Wehrlein Manor 1:24.297 +1.077 86 laps
6 D. Ricciardo Red Bull 1:24.307 +1.087 89 laps
7 P. Gasly Toro Rosso 1:24.821 +1.601 78 laps
8 A. Celis Jr Force India 1:25.467 +2.247 99 laps
9 A. Lynn Williams 1:26.071 +2.851 86 laps
10 E. Ocon Renault Sport 1:26.530 +3.310 104 laps