At the very front it was a mostly straightforward start to the race as Kostecki charged into the lead from pole, followed by Will Brown and Bryce Fullwood.
But there was plenty of drama right behind the lead group, starting with Mark Winterbottom smacking the Turn 5 fence while scrapping over fifth place with James Golding.
Turn 5 claimed another victim a lap later when Macauley Jones and Matt Payne made contact that sent Jones into the back of Anton De Pasquale.
The Shell Ford then speared into the wall and out of the race, with Payne later smacked with a drive-through penalty for instigating the shunt.
At the same time James Courtney pulled into pitlane with his Tickford Mustang suffering a significant engine fire similar to that seen in Nick Percat's car yesterday.
The veteran managed to get the car into the lane so that fire crews could intervene and then extricate himself safely.
The race went green again on Lap 6 with a time certain finish in place for Lap 11.
The immediate opening of the pit window meant Cam Waters, the only driver left in the field on hard tyres thanks to De Pasquale's issue, dived into the pits from the back of the field to take the super softs.
The super soft starters then started to hit the lane on Lap 9 for hards, the second-place team cars first to make their stops.
That was bad news for Brown who pitted from second, but was always going to lose several spots.
And that was the case, Kostecki pitting and retaining his lead from Will Davison and Fullwood and Shane van Gisbergen, and Brown slipped backed to fifth.
However the manic round of Lap 10 stops soon played into Brown's hands, with both Davison and Fullwood penalised for unsafe releases.
For Fullwood the issue was contact with Declan Fraser on his release, while Davison clobbered into one of van Gisbergen's tyres as he left his box and sent it flying.
Their respective 15-second penalties dropped them to 11th (Davison) and 12th (Fullwood) in the final standings.
Kostecki went on to win the race however he too wasn't spared a post-race investigation of his own into an unsafe release, given Fraser appeared to baulk as the Coca-Cola Camaro was released.
Update: Kostecki has kept his win after being cleared of any wrongdoing by the stewards.
As it stands van Gisbergen is second while Brown was re-promoted to the penalties thanks to the Davison and Fullwood penalties.
Chaz Mostert ended up fourth after surviving a mid-race tussle with Andre Heimgartner and James Golding that left the latter in a spin.
Heimgartner came home fifth ahead of Jack Le Brocq, Broc Feeney, Tim Slade, Thomas Randle and Waters, who made decent headway with his off-kilter strategy.
The Melbourne SuperSprint concludes with a final sprint race at 10:25am tomorrow.
