Matthew Parry finished practice at the Hungaroring in first place after setting a time of 1 minute 33.484 seconds, marginally ahead of the ART of Nirei Fukuzumi.
Championship leader Charles Leclerc was third, four thousands of a second ahead of Antonio Fuoco. Matevos Isaakyan, Alex Albon and Jake Hughes were next, all separated by five thousands of a second.
The fourth PREMA car of Nyck De Vries was eighth, ahead of Briton Jake Dennis and Indian Arjun Maini, the latter competing in his second GP3 race.
PREMA Powerteam will attempt to extend their lead the the teams' championship, with two of their drivers (Leclerc and Albon) looking set to battle each other for the series title.