Bargwanna improved to first with a 0:56.9340s on his third lap, before D'Alberto responded with a 0:56.7121s.
A lap later, Bargwanna went back to first with a 0:56.5234s, as Zac Soutar (Audi) moved up to second with a 0:56.5466s.
Sweeny went to the top with a 0:56.3556s, edging out then second-placed Brown by 0.0269s, with his lap a 0:56.3825s.
Soutar went to P1 with a 0:56.3335s on his seventh circulation, before Sweeny responded with a 0:56.2013s.
Brown went to first with a 0:56.1345s on his sixth pass, leading the standings after 10 minutes ahead of Sweeny, Soutar, Bargwanna, D'Alberto, with Aaron Cameron (Peugeot), Jordan Cox (Peugeot), Lachlan Mineeff (Audi), Garland and Tom Oliphant (Alfa Romeo) rounding out the top 10.
Brown further improved with a 0:56.0822s on his eighth lap, ahead of Sweeny with a 0:56.1995s also on his eighth pass, before filing into pit lane, where he was joined by the likes of Bargwanna, D'Alberto, Soutar, Minneeff and Oliphant.
All of that group barring Brown and Soutar returned to the track, with 18 minutes elapsed, as Cox improved to fourth with a 0:56.4595s.
Brown returned to the circuit shortly thereafter, as Bargwanna displaced Cox for fourth with a 0:56.3873s.
Cameron briefly moved to third with a 0:56.3294s, before Bargwanna claimed that position on the timesheet with a 0:56.3086s.
At the end of the session, it was Brown from Sweeny, Bargwanna, Cameron, Soutar, Cox, D'Alberto, Garland, Oliphant and Mineeff, as Iain McDougall (Audi) and Josh Buchan (Hyundai) completed the order.
TCR Australia will return to the track tomorrow for Qualifying at 13:20 local time/AEDT.