Racing Engineering's Fabio Leimer set a blistering lap early in the Friday practice session that left him a full second clear of the rest of the field.
Fabio Leimer continued to set the pace in the GP2 testing session at Jerez with the fastest overall time of the two days, but Lotus ART's Jules Bianchi came top in the afternoon session.
Following an operation to insert 21 pins into his leg to stabilise multiple fractures to his tibia and fibula, Davide Rigon is set to return home from Istanbul to Italy at the weekend.
Colini's Davide Rigon requires immediate surgery on Monday morning after sustaining multiple fractures to his tibia and fibula in the GP2 sprint race at Turkey.