The Englishman was 0.164 seconds ahead of the world champion, with Mercedes driver Nico Rosberg third ahead of the second McLaren of Lewis Hamilton.
Lotus drivers Kimi Raikkonen and Romain Grosjean were fifth and sixth.
Fernando Alonso was only 14th despite Ferrari introducing a number of updates aimed at improving performance.
Scot Paul di Resta was 15th as his Force India team, like all their rivals, tried out new parts in an attempt to gain competitiveness.
McLaren got off to a troubled start in the afternoon session, with Button twice complaining of "terrible understeer" and Hamilton saying his gear ratios were too long.
But after Vettel set the early pace as the drivers began their runs on the faster 'soft' tyres, Button usurped him a few minutes later.
Hamilton might well have been up with his fellow Englishman had he not made a mistake on his first flying lap on the soft tyres. He did his time on the second lap, by which time the rubber is past its best.
McLaren have one of the most obvious updates, introducing a new, higher nose design for this race, following the trend of virtually all the other teams.
Although Friday practice is notoriously unreliable as a guide to form, it was a dispiriting day for Ferrari.
Alonso was fastest from Vettel by 0.378secs in the first 90-minute session in the morning, as he tried out new rear bodywork, a new floor and new front and rear wings.
But the afternoon was a different story and he was 1.201secs adrift of Button. Team-mate Felipe Massa was 0.198secs ahead in 11th.
Like Hamilton, Alonso's first lap on the soft tyres was compromised - in his case by hitting traffic. Nevertheless, he was already more than 0.3secs off the pace at the first split point on the approach to Turn Four.
BBC F1 technical analyst Gary Anderson said the updates were a step in the right direction, and may make the car as much as 0.5secs a lap faster, but he added that all their rivals were moving forwards too.
BBC 5 live analyst Jaime Alguersuari, the former Toro Rosso driver, said: "I don't see Ferrari as contenders. They may have gained 0.3-0.4secs but I don't seem them as contenders for the win or the podium. I think they'll be struggling to get into Q3 still."
It was a low-key but quietly impressive session for Red Bull, where Webber appeared to be struggling to match Vettel's pace.
The Australian, who was seventh fastest, had an off-track moment at Turn Four, going into the corner too fast and bouncing across the gravel trap. He managed to reach the area of grass between the gravel and the tyre barrier and rejoin the track, albeit peppering the circuit with stones.
Alguersuari said: "McLaren look very competitive - they did a lot of laps on the soft tyre (in the race-simulation runs at the end of the session).
"I think it will between McLaren, Red Bull and Lotus."McLaren's Jenson Button beat Red Bull's Sebastian Vettel to set the fastest time in Friday practice at the Spanish Grand Prix.
BBC Sport
BBC Sport
Pos Driver Team Time Laps 1. Jenson Button McLaren-Mercedes 1m23.399 38 2. Sebastian Vettel Red Bull-Renault 1m23.563s + 0.164 38 3. Nico Rosberg Mercedes 1m23.771s + 0.372 41 4. Lewis Hamilton McLaren-Mercedes 1m23.909s + 0.510 32 5. Kimi Raikkonen Lotus-Renault 1m23.918s + 0.519 32 6. Romain Grosjean Lotus-Renault 1m23.964s + 0.565 37 7. Mark Webber Red Bull-Renault 1m24.065s + 0.666 34 8. Michael Schumacher Mercedes 1m24.080s + 0.681 36 9. Kamui Kobayashi Sauber-Ferrari 1m24.214s + 0.815 41 10. Nico Hulkenberg Force India-Mercedes 1m24.365s + 0.966 22 11. Felipe Massa Ferrari 1m24.418s + 1.019 35 12. Sergio Perez Sauber-Ferrari 1m24.422s + 1.023 32 13. Pastor Maldonado Williams-Renault 1m24.468s + 1.069 40 14. Fernando Alonso Ferrari 1m24.600s + 1.201 33 15. Paul di Resta Force India-Mercedes 1m24.688s + 1.289 30 16. Jean-Eric Vergne Toro Rosso-Ferrari 1m24.733s + 1.334 34 17. Daniel Ricciardo Toro Rosso-Ferrari 1m24.769s + 1.370 37 18. Bruno Senna Williams-Renault 1m25.047s + 1.648 42 19. Heikki Kovalainen Caterham-Renault 1m26.296s + 2.897 36 20. Vitaly Petrov Caterham-Renault 1m26.740s + 3.341 35 21. Timo Glock Marussia-Cosworth 1m27.314s + 3.915 27 22. Charles Pic Marussia-Cosworth 1m27.664s + 4.265 30 23. Pedro de la Rosa HRT-Cosworth 1m28.235s + 4.836 26 24. Narain Karthikeyan HRT-Cosworth no time 2 All Timing Unofficial
ليست هناك تعليقات:
إرسال تعليق