Johnny Cecotto Jr was quickest in both sessions as GP2 finished its last test of 2012 at Jerez.
After winning in Monaco during his season with Addax this year, Cecotto switched to Arden for the final day of the test, having driven for Carlin on Thursday.
He edged out Carlin's Felipe Nasr in the morning, when Auto GP champion Adrian Quaife-Hobbs was third in Arden's second car.
Thursday pacesetter Marcus Ericsson moved across to Coloni and took fourth, followed by Italian Formula 3 graduate Kevin Giovesi, who had also been quick for Lazarus on day one.
Giovesi had a less straightforward afternoon, stopping on track and causing a red flag. Other stoppages during the day were prompted by spins for European F3 champion Daniel Juncadella and Simon Trummer.
Stephane Richelmi, driving for champion squad DAMS, was Cecotto's nearest rival in session two.
Rene Binder kept Lazarus near the front with third place, followed by Stefano Coletti in the Rapax seat he has already secured for 2013, and iSport's Jolyon Palmer.
Nasr skipped the afternoon session so he could travel to this weekend's Brazilian Grand Prix.