Dry running has allowed teams and drivers to come to grips with Mount Panorama ahead of the Hi-Tec Oils Bathurst 6 Hour, Supercars star Anton de Pasquale topping the second 60-minute practice session on Friday.
De Pasquale's 2m27.402s best came early in the session with co-drivers Anthony Soole and Adam Burgess completing the remainder of the running throughout the session.
After a opening session interrupted by red flags and wet weather, the second session ran green for the first 45 minutes before the first stoppage, allowing teams to gather meaningful information for the first time today.
58 cars completed more than 600 laps between them this afternoon following a dramatic day of highly changeable weather, that at times shifted from thunderstorms to bright sunshine within the space of an hour.
BMWs filled the first six spots in practice two, with the David Russell / Karl Begg / Robert Gooley M4 second and the Michael Auld / Garth Walden / Tyler Everingham M3 in third.
Tim Leahey put the M3 he'll share with fellow former winner, Beric Lynton, and Supercars ace Will Davison into fourth position while the Ben Kavich / Micheal Kavich / Thomas Randle M2 Competition completed the top five.
Iain and Grant Sherrin, former winners of the race were sixth while Lindsay Kearns and Colbey Cowham were quickest of the A2 runners and seventh outright, while the Marcos Ambrose / Tim Brook / George Miedecke Mustang was seventh and second in class.
Class A1 was topped by Dylan O'Keeffe in the Mercedes AMG A45 he will share with Mike Sheargold and Brett Hobson - the RAM Motorsport / GWR entry ninth outright in practice two.
Jason Gomersall and Aaron Seton rounded out the Top 10 in their Ford Mustang.
Quickest in Class B1 was the BMW 135i driven by Rob Rubis, Scott Turner and TCR Australia star Jordan Cox, the little BMW an impressive 13th outright.
The Brad McDonald / Cody McKay / Brent Edwards Holden Commodore SSV Redline topped Class B2 and ended the session 36th outright.
Class C was again paced by the flying Mazda driven by Jake Camilleri and Scott Nicholas, the Queenslanders ending the day in 32nd outright; two spots ahead of their closest rivals, the Osborne Motorsport Renault Megane RS driven by Colin Osborne and Jay Robotham.
The Subaru BRZ of Scott Aho and Haydn Clarke topped Class D over the Ric Shaw / Tom Shaw / David Cox Mazda, while the quickest car in E was the Mazda of Stephen Doorey, Phil Alexander and Bathurstian, Shane Fowler.
A third and final practice session will give teams a final systems check before qualifying tomorrow.
Qualifying, to be held in two parts, will be broadcast live and ad-break free on Stan Sport while the battle for the outright pole position will also be shown live on the Nine Network around Australia.
International streaming will be available via www.speedseries.com.au/TV from midday, local time.
Click here for practice two timings.
Support categories daily wrap
There were four other categories in action today, including the Fanatec GT World Challenge Australia, Circuit Excel Bathurst Challenge, MRF Tyres Australian Pulsar Racing Association and the combined GT4/Australian Production Cars.
Running its first round of the season, the Fanatec GT World Challenge Australia had two practice sessions today and it was Triple Eight Race Engineering’s Jamie Whincup who ended the opening day with the fastest time.
Behind the wheel of the Mercedes-AMG GT3 he shares with Prince Abu Bakar, Whincup wound back the clock and set a 2m 05.690s in the afternoon session - a time that was more than half a second faster than the next best driver in Liam Talbot.
Click here to view a wrap on the day.
GT World Challenge Australia has two qualifying sessions in the morning before a one-hour race in the afternoon.
Kicking off the event in the morning was the MRF Tyres Nissan Pulsars and it was an unchanged top two all day as Joshua Craig went fastest in both practice sessions before securing pole over Dan Smith - remarkably just over a second separated the duo in all three sessions.
It was a similar story in the Circuit Excel Bathurst Challenge, which saw Ryan Casha fastest in practice and qualifying - although practice runner-up Ben Gomersall dropped to third in qualifying as Victorian Harry Tomkins claimed a front row finish.
The MRF Tyres Nissan Pulsars has all three of its races tomorrow, while the Excels will run two of its three throughout the day.
Rounding out today's results was the combined GT4/Australian Production Cars and it was Karl Begg who steered his Mercedes AMG GT to the category's fastest time for the day - his 2:31.9396 in on his second last lap for the afternoon unbeaten.
Before that, it was Grant Sherrin who was overall quickest - his 2:32.9178 in the morning not beaten by no one other than Begg, while Trevor Symonds was the fastest Production Car in the afternoon - almost five seconds off Begg in his Holden VE GTS.