Shane van Gisbergen led 1 minute 2.807 seconds early in the half-hour session.
New Zealander Andre Heimgartner then lowered the benchmark to 1m02.430s ahead of Cam Waters at 1m02.634s.
Friday pacesetter Anton De Pasquale made a short stop midway through the session, then Van Gisbergen was again fastest with 1m02 in .258s.
then Davidson hit the hammer with 5 minutes left, and the veteran set 1 minute 2.154 seconds despite not using the green rubber.
“Very good meeting, very productive,” Davidson said.
“We had a good run yesterday, we ran the second set [green tires] yesterday. But we know we were strong in the first set. We want to run the program, and this information is in Helped us a lot overnight.
“We were ready to run a new set of tires [today], but I’m happy with what we’ve done by reusing yesterday’s tires. We learned what we needed to do and there was no need to waste another plate. “
Heimgartner was second, just 0.01 seconds behind Davidson, while Chaz Mostert and Nick Puckart of Wokingshaw Andretti United were in second place. Also in
Van Gisbergen in De Pasquale, Waters, Scott Pye, Bryce Fullwood and David Leno Ziz made no progress in his final race and was dragged back to fifth.
It was a tough race for both Kostecki, Jake Kostecki was stuck at turn 4 In the sand, an early red flag was raised.
Brodie Kostecki was taller – late in the session accelerating on the last corner, driving his Erebus Holden into the wall.
” I’m really throwing up,” he said. I made a big mistake for lefties, too much curb and lost it between the corners.
“It ruined the left Links on the back toes. Thank goodness it wasn’t all that bad, but doing some work qualifying for the boys before qua is nothing good. “
Qualifying starts at 2pm local time.