There was a heated battle between the pair within the closing levels of the time sure race, each drivers making contact with the opposite as van Gisbergen executed a basic overcut technique.
Ultimately the end result went the way in which of van Gisbergen, who logged a primary Gen3 win after having his Saturday victory taken away as a consequence of a technical breach earlier right now.
It was Mostert that made the swiftest begin to the race, the Walkinshaw Ford driver leaping David Reynolds from the skin of the entrance row to take an early lead.
His cost solely final a number of corners, although, the protection automotive referred to as simply moments after the beginning as a consequence of a conflict between Declan Fraser and Macauley Jones on the entrance straight.
Fraser seemed to show throughout the entrance of Jones as they pulled away from the grid, which resulted within the Tickford rookie being fired head first into pitwall.
The next injury to the limitations led to the warning changing into a pink flag in order that repairs might happen.
The race resumed below the protection automotive on Lap 3 earlier than going inexperienced at on Lap 5, Mostert main Reynolds, Cam Waters, James Golding and van Gisbergen.
That was the order for a lot of the primary stint till Mostert hit the lane for his first cease on Lap 23.
It wasn’t till six laps later than Waters did likewise, adopted by Reynolds a lap later, which dropped him again behind each the Monster Mustang, and an early-stopping Broc Feeney.
Across the similar time van Gisbergen handed Golding on observe earlier than setting off on an extended first stint.
The Kiwi did not make his first cease till Lap 38, resuming in fifth behind Reynolds, till Reynolds was capable of clear Feeney for third.
By Lap 46 van Gisbergen would additionally get previous Feeney, though at that time he was nonetheless 17s behind the leaders.
The hole on the entrance was nearer, although, with Waters pulling up proper behind Mostert on Lap 47.
A lap later Waters pushed barely too onerous into Flip 9 in pursuit of Mostert, clipping the within wall and bending a steering arm.
He took his second cease on Lap 49 with the crew endeavor prolonged repairs on the arm, which took him out of rivalry for the win.
Two laps later there was one other change close to the entrance of the sphere, van Gisbergen taking on second on the highway from Reynolds on the final nook.
Van Gisbergen had additionally labored the hole to Mostert right down to 10s as he used his a lot brisker rubber.
The Kiwi continued to work down that hole till Mostert stopped for brand spanking new tyres on Lap 58.
Reynolds was the subsequent to cease on Lap 68, a gradual cease due a wheel problem and a few set-up modifications dropping him to fourth behind Golding. He was capable of work his method again previous the PremiAir Camaro thought to reclaim the ultimate spot on the rostrum.
Van Gisbergen then made his last cease on Lap 70, resuming round 8s behind Mostert with a time sure end looming.
The pair then picked their method by means of lap site visitors as they bolted to the flag, van Gisbergen closing to inside three seconds because the race entered its last 10 minutes.
With the site visitors cleared van Gisbergen was capable of correctly use his tyre benefit, the hole right down to inside a second with 5 minutes left.
The race peaked a number of laps later when van Gisbergen nudged Mostert broad at Flip 9 to take the lead.
Mostert did his finest to battle again on the penultimate nook as he returned serve on van Gisbergen, nonetheless whereas the Kiwi ran broad he nonetheless had the road for the ultimate nook and retained the lead.
As soon as in entrance he needed to the grip to bolt into the lead, crossing the end line 4.4s away from Mostert.
“All I’ve to say is thanks to the Pink Bull Ampol Racing Staff,” mentioned van Gisbergen.
“Yesterday was powerful however we’ll battle it. The group knuckled down and did a superb job. The remainder of it, I did all my speaking on observe.”
Mostert mentioned: “[The pass] was slightly bit cheeky. I do not thoughts rubbing is racing, however whenever you get a transparent move from it, it’s kind of cheeky.”
Reynolds got here dwelling third forward of Golding and Feeney.
Brodie Kostecki was sixth from Andre Heimgartner and Jack Le Brocq, whereas Tim Slade and Mark Winterbottom rounded out the highest 10.
Waters dropped again to twelfth after his brush with the wall, whereas for the second day working neither Dick Johnson Racing Ford made the highest 10, Anton De Pasquale sixteenth and Will Davison nineteenth.
The Supercars season continues on the finish of the month at Albert Park.