A post-race fine and teams' championship penalty added to a difficult Sunday for IRWIN Racing and Mark Winterbottom at Winton.
Winterbottom started sixth and finished ninth on Saturday, but ended the second leg in 22nd place and a lap down.
From 17th on the grid, Winterbottom's race "went pear-shaped" in a tangle with Simona De Silvestro's Nissan at Turn 1 exiting the pits after his first stop.
That punctured a front-right tyre on Winterbottom's Commodore and incurred a 15-second time penalty from stewards, ending his hopes of another top 10 result.
Winterbottom noted he "didn’t see Simona and somehow ended up with a penalty for staying on the inside [line] coming out of pitlane and getting turned down on".
Post-race, the squad was fined $3,000 and docked 30 teams' championship points for a line-locker breach during a pitstop.
"Tough race on Sunday, didn’t have outright speed but had quite good tyre life in the race," Winterbottom said.
"The lap I did before we pitted was quite competitive, I pitted and went back out, one car passed me and then made contact with De Silvestro.
"Very surprised [at the 15-second penalty], I’ve never seen anyone get one for something like that. I couldn’t go anymore left.
"The steering was bent, had no radio communications so it was a long way home."
Winterbottom leaves Winton 11th in the points, ninth on Saturday his first top 10 finish since the Symmons Plains event in April.
But even that run to ninth came with a unique challenge.
"Really struggled around right-hander turns," he said.
"Not sure why hopefully we find a problem because it’s pretty strange to have a car that goes good one way but not another.
"All those struggles but we still finished P9."