Mostert and co-driver Holdsworth have been on the pace since practice for the Bathurst 1000 started on Thursday morning.
The #25 Holden has been in the top three in every single session, including topping four of the six practice sessions.
The crowning glory was an incredible lap from Mostert in the pole-deciding Top 10 Shootout, his 2m03.373s the fastest ever for a Supercar around Mount Panorama.
Reflecting on the lap with Fox Sports presenters Jess Yates and Mark Skaife, Mostert agreed that it was the best he’s ever done – even though he admitted he clipped the wall at Forrest’s Elbow.
He also spoke about an “effortless” quality to the lap, thanks to how well the car has handled since it rolled out of the truck on Thursday.
“I reckon yeah, for sure,” he said when asked if it was his greatest lap.
“I don’t know what I did at the Elbow. I probably didn’t need to whack the fence. I think I just got excited on the exit. I couldn’t believe how it got across the top, and then I got the Elbow going, ‘I just snagged the fence but I don’t think I needed to’.
“It’s funny, the car is so smooth to drive. Through the Cutting I felt like I was in a GT3 car. The car floated across the top. It picked up grip.
“It’s so fun. I can’t put [the lap] into words. When you’ve got such a good car underneath you it kind of becomes effortless. You still make sure you hit all your markers, but your margins are all opened up and you just flow the speed.
“That’s the trick with our car. The flow speed his weekend is amazing.”
Mostert added that the single-lap pace was slightly surprising given the team had been more impressed with the car’s consistency during practice, rather than its outright speed.
“Before qualifying we thought we had a better race car than a qualifying car, so I’m glad the track has been coming to us,” he said.
“In the warm-up tomorrow we’ll really focus on making sure we nail our race car for tomorrow.
“But it’s just good to start on the front row, get some clean air and we’ll see what we can do in the race.”
The Bathurst 1000 pole is Mostert’s second, although the only the first he can properly celebrate given his first in 2019 wasn’t formally awarded to him until well after the race weekend.
That year Scott McLaughlin set what was temporarily a Bathurst lap record, a 2m03.378s, in the Shootout, only for his motor to fail post-event technical checks.
The Kiwi was stripped of his pole and it was retrospectively awarded to then-Tickford driver Mostert.
For Walkinshaw Andretti United, meanwhile, the pole is the team’s first at Mount Panorama since 2009 when it was known as the Holden Racing Team.
That year Garth Tander and Will Davison combined for one of the team’s seven Bathurst 1000 crowns.
“[The pole] is really awesome for our whole team,” said Mostert.
“You see the effort that they put into this race. The history of this team is amazing around here. The effort they put in is the first thing I noticed about this team. They live for Bathurst.”
The 2021 Bathurst 1000 kicks off at 12:15pm local time tomorrow.