|Sebastian Vettel racked up more laps than anyone else on Mar 6. (AFP/LLUIS GENE)|
The four-time world champion clocked 1min 20.396sec at the Circuit de Catalunya, finishing two tenths quicker than Valtteri Bottas with Max Verstappen of Red Bull a close third.
"It was a good day's work," said Vettel after completing 171 laps, the most of any of the 13 drivers who took to the track.
"We managed to get through our programme, even if the conditions weren't always ideal, because of the wind."
Defending champion Lewis Hamilton was 0.412sec back in fourth as those in action took advantage of the improved weather to rack up a combined total of 1,137 laps.
"It's been a good day," the Briton said. "We've got through everything we needed and put good mileage on the car - it's been productive.
"The biggest challenge we faced today was to get the tyres working properly on this new track surface."
McLaren endured a difficult session, however, as Stoffel Vandoorne came to a halt on just his fourth morning lap, his MCL33 car suffering a sudden power cut.
The new season begins with the Australian Grand Prix in Melbourne on Mar 25.