The session, just the second for the new Gen3 cars, got off to a fast start, Andre Heimgartner pipping his Practice 1 time on his first run with a 1m11.983s.
From there is settled into a slower rhythm, though, as focus switched to race runs and pitstop practice.
It wasn't until the 20-minute mark that the next change came at the top, Will Davison lowering the benchmark to a 1m11.792s.
There was then another 10 minute break until Shane van Gisbergen went slightly quicker again with a 1m11.755s.
That was it in terms of noteworthy changes in the order with teams opting against qualifying sims in the final quarter of an hour.
That left van Gisbergen three-hundredths clear of Davison at the top, while Broc Feeney capped a good session for Triple Eight in third.
Chaz Mostert, who lost time during the session with a stubborn wheel, ended up fourth. The WAU driver did go green in the first sector on his final run but hit traffic later in the lap.
Scott Pye logged Team 18's best result of the day so far with the sixth fastest time right ahead of teammate Mark Winterbottom.
Anton De Pasquale and Cam Waters were next while James Courtney rounded out a top 10 that was separated by less than half a second.
The first official day of running with the new Gen3 cars will conclude with a third 45-minute practice session at 3:50pm local time.
