The first half-hour session of the weekend was top heavy in terms of improvements on the time sheets.
Most of the field rolled out on green tyres with the faster times all coming in the first 10 minutes.
Initially it was van Gisbergen and the Erebus drivers trading blows at the top, before the Kiwi settled in top spot with a 1m30.494s.
Nobody would go quicker than that as focus shifted to longer runs.
Being quickest did come as somewhat of a surprise to van Gisbergen who felt he wasn't able to push his Gen3 Camaro around the fast, flowing Sydney layout.
He did, however, give his new chassis the thumbs up, having switched to T8's spare after tracking issues at the last couple of rounds.
"I don't know if I loved it, but it felt different," he said.
"I don't know, we're obviously good but I feel like I'm driving around on wets. You're driving at 40 per cent trying to keep the car on the track.
"You want to push, but you just can't push these cars. The way the car works, it likes to be finessed and driven slowly.
"[The car] is fine. It drives down the straight straight, rather than variable steering, which is nice. We have the other car here, we can try it on the ride day. The guys think they figured it out what it was, but we just changed chassis to be safe."
Matt Stone Racing driver Jack Le Brocq ended up second fastest, having set a 1m30.682s moments after van Gisbergen set his time.
Erebus pair Brodie Kostecki and Will Brown finished up third and fourth fastest, while Chaz Mostert was one of only two Fords in the top 10 wait the fifth fastest time.
James Golding recovered from an early spin at turn 3 to end up sixth ahead of Broc Feeney, Andre Heimgartner and Tim Slade.
Nick Percat rounded out the best 10 as the only other Ford driver along with his teammate Mostert.
Anton De Pasquale, a winner last time out, led the way for Dick Johnson Racing in 12th after battling some steering issues early in the session.
Will Davison, meanwhile, had more significant steering issues in the other DJR Mustang, which needed a rack change during the session.
That meant he only completed three laps and spent the rest of the session in the garage.
"Very, very costly," he said. "We just had no feel, the car had a huge amount of play in it. I couldn't drive the car the way it was.
"Pretty costly with this two-day format, to be sitting in here the whole session."
Practice continues at 2:10pm local time.
