But with few points to gain from a dangerous and potentially morale-sapping move on his teammate, McLaughlin was happy enough to coast to second place ahead of surprise podium debutant Anton de Pasquale.
Coulthard said he was slightly shocked to emerge with the race lead after the dust settled on the pit stops.
“I’m not sure what happened to Scott on one of his out laps,” he said.
“But I’m pumped. It’s awesome for all my guys.
“It’s always hard to get the first one (of the year). I’ve got a class teammate, simple as that – to take one off him is tough at the best of times.”
Penske managing director Ryan Story reported a two-second difference in “pit transit time”, suggesting McLaughlin was slow on entering or exiting the circuit’s pit lane, one of the longest in the calendar.
McLaughlin was the first man to congratulate Coulthard and praised his teammate but was eager to get to the bottom of his blunder.
“We have to have a look around, have a bit of a think,” he said.
“It’s great for the team.
“I’m really happy with my weekend … it’s been a big two weeks on the road so to come away with three one-twos is fantastic.”
He denied holding back from an overtaking effort, saying “we were both going hammer and tongs … that was all I had”.
De Pasquale, who claimed a first podium in his 41-race career, was the only Holden in a sea of Fords at the top of the order.
Rounding out the top six was Will Davison, Chaz Mostert and Cam Waters as the Mustangs continued their supreme start to the series.
After ten races, Fords have won nine.
McLaughlin, racing for a back-to-back title, has seven of those and now leads the championship by 124 points over Coulthard.
Mostert has improved to third, a further 119 points behind.