Shell Ford pair Scott McLaughlin and Fabian Coulthard led Jamie Whincup in opening practice at Pukekohe as the three title contenders showed the way.
The first 40 minutes of track running for the weekend took place in overcast but dry conditions, with rain expected to arrive in the afternoon.
McLaughlin set an early 1:03.0806s benchmark as the drivers felt out the circuit’s recently resurfaced patches.
The time stood until McLaughlin returned with a second set of tyres for his final run, moving a full 0.6 seconds clear of the field with a 1:02.7153s six minutes from the end.
Coulthard drew within 0.1678s just prior to the chequered flag being shown to sit second ahead of Whincup, who was 0.2251s shy of the pace with his final effort.
McLaughlin and Coulthard both had spins at the Turn 8 hairpin during the session, while several others made trips through the run-off at the Turn 5/6 chicane.
“It might rain this afternoon, so it’s nice to get a little feel for it for qualifying tomorrow if it is dry,” explained McLaughlin.
“The car feels nice, [we had] a couple of little offs, but just trying to find the limit.
“The track’s quite green, there’s not that much grip out there at the moment. I think with all the rain and stuff it’s pretty low grip.
“Trying to brake where you did last year and stuff just isn’t working, and some of the parts of the track are also degraded.
“It’s OK, as long as we’re fast, that’s the main thing.”
Coulthard enthused that the team has “a lot to work with” from the session.
“It’s nice to get a dry session in there before it rains, if it’s going to,” he said.
“We’ve got some good things to look over, Scotty did a great job, my car’s pretty good. We’ll make it better and go again.”
Other late improvers Tim Slade, David Reynolds, James Courtney, James Moffat, Lee Holdsworth, Craig Lowndes and Jason Bright completed the top 10.
Chaz Mostert sat second for the bulk of the session but fell to 11th after failing to improve in the closing stages.
Mostert spent the early part of the session readjusting to his Supercar after racing a GT3 BMW in China last weekend and says more tuning is required on the Supercheap Ford.
“Obviously it’s a pretty bumpy track, we rolled out fairly similar to what we do at other places, just we need to work on the car a little bit,” he noted.
Shane van Gisbergen was just 19th after spending the final 25 minutes in the garage while the team undertook major set-up changes ahead of this afternoon’s second session.
“We just tried a lot of stuff for this session thinking it would work, it has in the past, but no good,” he said.
“So rather than waste time and tyres we’ll make it better for the second session, hope it’s dry and try again then."
The defending Jason Richards Trophy winner said his struggles were unrelated to the resurfacing works, praising the upgrades.
“They’ve done a good job,” he added. “It’s a nice surface, it’s got rid of all of the aggressive bumps but still kept some character.
“The track’s pretty awesome to drive, still enjoy it, just hope we can make the car better.”
It was a difficult opening session for Lucas Dumbrell Motorsport, with both cars striking trouble.
Jack Perkins slid wide entering the pit straight during his first run, dragging the left side of the #62 Holden down the concrete.
Although able to drive back to the pits, Perkins – who has replaced Alex Rullo this weekend - spent the remainder of the session in the garage.
Aaren Russell spun his #3 LDM Commodore at the high-speed Turn 1 with 11 minutes remaining, ending up stranded in the gravel, triggering the session’s only red flag.