"Definitely a better day today," Vettel, who only managed 14 laps on day one, said in a Red Bull statement.
"We did more laps, so that's encouraging. It's good to check the car, check the reliability, but obviously there is a lot still to do.
"It was good to get a proper first feel for the car and it feels OK but there's a lot more to come."
Dane Magnussen continued to build on his impressive start in Formula One by completing 46 laps and setting the day's fastest time of one minute 34.910 seconds.
Force India's Nico Hulkenberg was over 1.5 seconds slower than Magnussen, setting the second quickest time of 1:36.445 during his 59 laps.
Valtteri Bottas of Williams notched 116 laps, the most of any driver, and former world champion Fernando Alonso covered plenty of ground for Ferrari with 97 laps and the day's third fastest time.
Lotus announced that Frenchman Charles Pic will be the team's reserve driver this year following his departure from Caterham.
(Reporting By Mark Pangallo in London, editing by Ed Osmond)
