After a cold start to the morning with temperatures reaching just 5'C, the track heated up and so did the action.Vettel, who topped the timesheets on Friday with a 1:24.374, went a full second quicker on Saturday, crossing the line with a 1:23.315.
But it wasn't all smooth sailing for the reigning World Champ, who had to abandon his race simulation in the afternoon after his Red Bull mechanics noted a problem with his RB7.
Toro Rosso driver Jaime Alguersuari was a surprise in second place, finishing two-tenths behind Vettel while Fernando Alonso had to settle for third place in his late charge.
The Spaniard was another to run into problems on Saturday, bringing out the day's first red flag just half an hour in the session when he stopped at Turn Four.
Ferrari said on Twitter: "Not a good start of the second day of the session. Fernando stopped on track due to an electric problem. Anyway, the issue has been solved. Tyres and set-up changes are the main objectives of today's programme."
However, the Spaniard's running was again hampered in the afternoon as his F150th Italian countered mechanical problems, keeping Alonso down to 90 laps.
In sharp contrast, Rubens Barrichello and Williams finally had a trouble-free day with their FW33 and the Brazilian finished in fourth place, ahead of Lotus Renault driver Nick Heidfeld.
The German, who is filling in for the injured Robert Kubica, split the duties with Vitaly Petrov and proved to be over two seconds quicker than his Russian team-mate.
Kamui Kobayashi was sixth for Sauber, finishing ahead of Nico Rosberg. The latter will be delighted to have completed a massive 131 laps after seeming to suffer the bulk of Mercedes GP reliability issues.
"We completed a great deal of mileage and that was important for me to understand more about the tyre behaviour," said Rosberg.
"There is a lot for the drivers to learn about how the Pirelli tyres are performing, and about how to make them last over the long runs; it's going to be a key factor this year in the races and I think we made good progress on that front today.
"The reliability was ok but everybody in the team knows we need to keep pushing to make sure we are trouble-free for the start of the season."
It was another quiet day for McLaren with a hydraulic problem forcing Jenson Button to miss most of the morning session. He was 1.608s adrift of Vettel's P1 time.
Paul di Resta and Heikki Kovalainen, who had problem with his T128 when its "collector filter was blocked" completed the top ten.
Times
01. Vettel Red Bull 1:23.315 104 laps
02. Alguersuari Toro Rosso 1:23.519 + 0.204 97 laps
03. Alonso Ferrari 1:23.978 + 0.663 90 laps
04. Barrichello Williams 1:24.008 + 0.693 118 laps
05. Heidfeld Lotus Renault 1:24.242 + 0.927 41 laps
06. Kobayashi Sauber 1:24.243 + 0.928 125 laps
07. Rosberg Mercedes 1:24.730 + 1.415 131 laps
08. Button McLaren 1:24.923 + 1.608 54 laps
09. Di Resta Force India 1:25.194 + 1.879 80 laps
10. Kovalainen Team Lotus 1:26.421 + 3.106 58 laps
11. Petrov Lotus Renault 1:26.884 + 3.569 61 laps
12. Liuzzi HRT 1:27.044 + 3.729 70 laps
13. Glock Virgin 1:27.242 + 3.927 66 laps
14. Teixeira Team Lotus 1:31.584 + 8.269 26 laps
Source: Planet-F1
