Rick Kelly has been docked 25 points for a clash with Garth Tander on the final corner of Race 28 at Sydney Motorsport Park.
The contact occurred as the pair fought for 12th place and saw Tander spin, demoting the Holden Racing Team star to 18th in the final result.
Tander was left frustrated by the incident, saying over his team radio that the Nissan “drove straight into my rear bumper”.
“It's not ideal to finish the race on a last corner incident, like that with Garth,” said Tander's former team-mate Kelly post-race.
“He was a little wide, and I got my nose underneath him, he turned in and there was contact.”
The penalty is Kelly's first for a diving infringement in four years.
The two-time Bathurst 1000 winner drops one place in the championship standings to 16th with the penalty, losing out to Tander's Walkinshaw team-mate Nick Percat.
Tander had earlier in the race been turned around by Kelly's team-mate Michael Caruso at Turn 6.
An investigation into that incident took place post-race, with no breach of the rules established.