Friday at the Thrifty Newcastle 500 proved a learning experience for drivers and teams after a bumper first competitive day of the new era.
The first day of the Gen3 Camaro vs Mustang rivalry delivered in spades, with four drivers from four different teams were covered by 0.1581s.
Brodie Kostecki planted his #99 Coca-Cola Camaro atop the timesheets, edging Shane van Gisbergen to make it a Camaro one-two.
Chaz Mostert was the first Ford home in third. The top three were covered by less than 0.1s, with Nulon Racing's Tim Slade and James Golding filling the top five.
At the surface, the day ran smoothly for all 25 cars, which stayed off Newcastle's close concrete walls in three 45-minute sessions.
Three cars clocked 70 or more laps of the 2.6km circuit across the three sessions: Bryce Fullwood's Middy's Camaro, Jack Le Brocq's Truck Assist Camaro and Nick Percat's Mobil 1 NTI Mustang.
All up, the 25 cars completed 1579 laps, or 4105km of running.
That's not to say the cars weren't hard to drive; rather, many drivers struggled at the likes of Turn 1, Turn 2 and Turn 11.
Notably, Will Brown also hit trouble at Turn 8 in Practice 3, and gently nudged the tyre barriers.
Van Gisbergen still managed to top Practice 2 and end up second in Practice 3, despite encountering a number of wobbles during Friday.
"The track was quite difficult when we first got out there and I felt like a bit of a wobbler for the first few laps and having a few dramas which was really tough," he said.
"Over the course of the day, I started to get a handle of everything. I had a longer run in the final practice session today and felt like we were getting better and better.
"I noticed that there were a few drivers struggling out there."
Andre Heimgartner — who topped Practice 1 — ended the day with the 14th quickest time.
"It was like aeroplane —up and down. But it was alright, I think we learned a lot," Heimgartner said.
"We've still got some problems to solve overnight to be there, but I think for our car it's positive overall — we're pretty speedy on the used tyre which is good.
"Hopefully we make some changes overnight and then we'll get it going on a green tyre."
David Reynolds was 21st quickest on Friday aboard his Penrite Ford, but suggested there was plenty more in the #26 Mustang.
"I think our pace relative to the rest of the field was quite strong," Reynolds said.
"We were always in the top five for the majority of the day until right at the end when we put new tyres on, and we just probably didn’t get the most out of them.
"We’ve learned a lot about this car today — the limits of what not to do and what to do.
"We’ve got our eyes wide open, our minds wide open to figure out what’s the best plan for tomorrow."
Will Davison was seventh quickest on Friday in the #17 Shell V-Power Mustang, and reiterated the challenges of debuting a new car at such a "violent" street circuit.
"We’ve obviously been counting down for months for today so it was a pretty special day," Davison said.
"A lot of track time, we learned a lot and we tried a lot. It’s a pretty violent track so it was really good to start understanding this package.
"Some changes were great, some were not so great. Our pace seems to be there or thereabouts – it’s incredibly close."
Teammate Anton De Pasquale added: "We’re trying heaps of different things.
"We don’t really know exactly how to make these things faster, not just yet."
Cars will roll out for ARMOR ALL Qualifying at 11:15am local time on Saturday.
The first Top Ten Shootout of the Gen3 era will commence at 12:35pm, which will set the grid for Race 1 at 3:20pm.
Tickets for the Thrifty Newcastle 500 are on sale on Supercars.com and Ticketek.com.
Thrifty Newcastle 500: Best laps and total laps