McLaughlin jumped polesitter van Gisbergen off the start line to lead through the opening stint of the race, which came to life when the Safety Car was called on lap 12.
The cause was Chris Pither’s Team Sydney Holden stranded in the Turn 11 barriers, sparking a flurry of pitstops.
Van Gisbergen unexpectedly emerged from the lane in front, having caught their Ford rivals napping with a shorter fuel stop – despite Shell holding the advantage of the top pit bay as 2019 teams’ title winners.
From there, the #97 Commodore cruised to maintain a five-second lead by the second round of pitstops.
Stopping one lap after McLaughlin, van Gisbergen returned to the track with his lead intact – or so it seemed.
It soon became clear that the Red Bull Holden had not taken the full remainder of its required fuel drop, a blunder necessitating a third stop.
Van Gisbergen did so 10 laps from the end, surrendering a nine-second lead and returning in fourth with fresh tyres for a late charge, although a suspension issue soon reared its head.
That left McLaughlin with a clear run to the flag, backing up his second on Saturday with a 10-second victory from Walkinshaw Andretti United’s Chaz Mostert.
"Full credit to Shane and his team, they really should've won that race," said McLaughlin. "They had the faster car, so I'll take it, we've got to take the luck when we can."
Mostert jumped a gaggle of cars with a clever strategy after taking on extra fuel at his first stop.
"We were obviously pretty lucky with the Safety Car, but still probably had the same pace as a podium today, so we'll take it," he said.
Tickford duo Cameron Waters – who lost time overshooting pit entry on lap 43 – and Will Davison came close to overhauling the #25, to no avail.
Waters stayed glued to the back of the Commodore, holding onto third as van Gisbergen closed in.
The Monster Energy Mustang was let off the hook when van Gisbergen suffered a right-front suspension failure, leaving him forced to park his car with just four laps remaining; a tough break after a sensational drive.
Van Gisbergen was picked up on the warm-down lap by Waters to the cheers of fans.
Davison was gifted a solid fourth, ahead of early stoppers Jamie Whincup and Lee Holdsworth.
Nick Percat, David Reynolds, Fabian Coulthard and Andre Heimgartner completed the top 10.
Reynolds could be in for an awkward post-race debrief after spinning teammate Anton De Pasquale at Turn 9 on the opening lap while trying to pass Mark Winterbottom.
That put De Pasquale’s rotated #99 in the line of fire, with Scott Pye the unlucky driver to collect him; heavy damage eliminating both on the spot and causing an early Safety Car.
Penrite Racing boss Barry Ryan was concise in his assessment of the incident – “shit happens” – while De Pasquale did his best to hide his disappointment on the broadcast.
“Not good, especially in Adelaide when you want to start the year off strong,” said De Pasquale.
“Obviously it's not ideal and because it's a teammate it obviously makes it a bit bigger.”
Bryce Fullwood and Macauley Jones were also involved in a subsequent pile-up but were able to press on, though both had later dramas including a visit to the Turn 11 barriers for the WAU rookie.
A day after claiming Kelly Racing’s maiden top 10 in a Ford, Rick Kelly endured an eventful run to 13th.
Kelly had been placed nicely inside the top 10 in the first stint before getting delayed in pitstop chaos, blocked by a double-stacking Jack Smith.
Smith was hit with a 15-second time penalty, adding to his horror weekend, before Kelly copped the same sanction for passing James Courtney under yellow flag conditions into Turn 9.
Garry Jacobson was the last of 20 classified finishers, six laps down after hitting the tyre bundle on the exit of Turn 14 after contact with Kelly.
McLaughlin leaves Adelaide with a 27-point advantage over Whincup in the standings, with Mostert an encouraging third.
Van Gisbergen’s DNF leaves the 2016 champion down in 13th overall, already 159 points behind McLaughlin.