Tickford Racing’s Chaz Mostert was second, 0.7729s adrift. He spent the bulk of the session second, and secured the place with a late flyer.
Penrite Racing’s Anton De Pasquale was the first of the Holdens in third ahead of Tickford duo Cameron Waters and Lee Holdsworth.
Factory Holden drivers Shane van Gisbergen and Jamie Whincup were just 20th and 24th respectively, continuing their lacklustre Friday form.
Van Gisbergen had a wild session, spearing off the road four times in the first 15 minutes of running.
The last of those came at the high-speed Turn 5 and left the Kiwi flexing a sore wrist.
Van Gisbergen sat last when the chequered flag fell, before recording 20th with a final effort, noting over the radio that he’d “finally completed a lap”.
“We’re not in a good place,” said Whincup. “There’s no secrets, we have got a lot of work to do, we’re just trying to find a balance.
“We don’t have front, we don’t have rear and we just don’t have overall grip as well so we have got a bit to do.
“But as I said, there is hope there, there is hope that we can still tune it up for qualifying, but we need to make the right calls. We need to make educated guesses and make right calls in the next hour or so.
“As a general rule, the most important thing is getting the car into the corner and setting the corner up but we’re struggling to do that this weekend.”
Also down the order was McLaughlin’s team-mate Fabian Coulthard, who managed just 15th.
The session featured an early red flag to retrieve debris from the front straight, after Macauley Jones ran wide and collected a foam sponsor sign on the entry to the main straight.
Knockout ARMOR ALL Qualifying will kick-off at 12:35pm local time.