The HMO Customer Racing Hyundai driver found himself alone on the front row at the start courtesy of some pre-race drama for Dylan O’Keeffe.
The polesitter had an issue with his Garry Rogers Motorsport Renault on the way to the grid, and while the team were able to get the car running, O’Keeffe was penalised for lifting the bonnet on the grid.
That meant he started from pitlane and Buchan had the front row to himself.
The Hyundai ace didn’t win the start, though, that honour going to John Martin who surged into the lead in his Wall Racing Honda.
But Martin didn’t have the pace to hold off Buchan for long, the lead changing hands a few laps later after a bold move around the outside going into the fast first corner.
Once in front there was no stopping Buchan, his final winning margin over James Moffat and Chaz Mostert more than three seconds.
“To see the podium, and I’ve got Chaz Mostert and James Moffat next to me… I watched these guys race around Bathurst as a kid. I’m really happy,” he said.
Referencing the pass on Martin for the lead he added: “You’ve got to do it. I wasn’t going to die wondering. It was a bit trophy or trees and I got a trophy.”
Moffat followed Buchan through on Martin before going on to finish a lonely second place. Series leader Mostert, meanwhile, made good progress to snare the final spot on the podium.
As for Martin, hopes of clinging on to the top three were dashed late in the race when his pace nosedived due to what seemed to be a technical problem.
He ended up dropping right back to 12th by the finish.
His teammate Tony D’Alberto fared better with fourth place followed by HMO’s Nathan Morcom and Garry Rogers Motorsport pair Michael Caruso and Jordan Cox.
Lee Holdsworth (ASM Alfa) and Aaron Cameron (GRM Peugeot) were next, while O’Keeffe worked his way back to 10th.
The TCR Australia action continues with two more races tomorrow.