Most of the drama happened before the start of the race with the entire front row taken out of contention.
For pole winner Will Brown the issue was a broken input shaft on his Audi, the Melbourne Performance Centre unable to source a spare in time for the race.
As it stands it's still not clear if the required parts will be delivered in time for tomorrow's pair of races, which could mark a significant blow for the title favourite.
Privateer Audi driver Zac Soutar, also in the latest-spec RS3, suffered the exact same issue in Qualifying 1 (where he was third fastest), his weekend also seemingly out on the spot.
Josh Buchan, who had qualified second, was then demoted to the rear of the field due to an overboost issue with his HMO Customer Racing Hyundai during qualifying.
The issues for Brown and Buchan promoted Sweeny and his HMO Hyundai to pole for the 30-lapper as he started as the lone car on the front row.
He did, however, have reigning champion Tony D'Alberto (Wall Racing Honda) and Aaron Cameron (Garry Rogers Motorsport Peugeot) right behind on the second row.
It was Cameron who looked to make the best of the start to the race, although his momentum left him awkwardly stranded on the outside of Turn 2 as he tried to get around Sweeny.
Running narrowly wide proved costly, Cameron dropping to fifth as D'Alberto and Kody Garland (GRM Peugeot) dropped into second and third respectively.
That was as close as anybody got to challenging Sweeny, who swiftly settled it a lead he would hold until the finish – at which point his advantage was a healthy 7.6s.
"That's an awesome start to the year," he said.
"We kept it clean and the car was fast, so it was a mega race. I'm happy with how everything went, it's the best possible start to the season.
"Hopefully we can keep momentum and try and string this championship together."
D'Alberto kicked off his title defence with a rather lonely second place, while Ben Bargwanna (GRM Peugeot) pushed Garland to the flag as they battled for third, but couldn't find a way through.
Cameron never recovered any spots from his early off and had to settle for fifth, ahead of the battle of the race between Jordan Cox (GRM Peugeot) and Buchan for sixth place.
As tense as the battle was, Buchan admitted afterwards that he was happy to settle for seventh and take a second-row start for the inverted top 10 Race 2 tomorrow.
"That puts me on the second row for tomorrow, so I was thinking more about that than getting the extra spot, and starting a row back," he said.
"I wasn't too upset with seventh. We're still a quick car by the looks of things so we'll press on tomorrow."
British Touring Car Championship race winner finished his TCR Australia debut in eighth in his Ash Seward Motorsport Alfa, followed by Lachlan Mineeff (MPC Audi) and Michael Clemente (Michael Clemente Motorsport Audi), who will start Race 2 from pole.
The remaining races for the weekend will take place at 1:30pm and 4:10pm local time tomorrow.
