Co-drivers. Who needs them?

Jamie Whincup and Mark Winterbottom could be forgiven for nasty thoughts about their co-drivers after a tense Sandown 500.

Whincup’s co-driver Paul Dumbrell and Winterbottom’s partner Dean Canto were guilty of lapses that cost their senior drivers dearly on the championship standings.

The Red Bull Racing pairing was poised to challenge for their third Sandown crown together until the changeover of drivers.

Dumbrell slipped his arm out early from his seatbelt and was served a drive-through penalty as a result.

He Dumbrell sheepishly admitted his mistake from the garage, where he watched Whincup finish 13th.

“I had a little brain fade,” he said.

“It’s really disappointing for J Dub and the boys … unfortunately those things happen.”

Whincup ceded the championship lead to Shane van Gisbergen, who placed second on Sunday, after the bungle.

The six-time series champion said he didn’t hold anything against Dumbrell.

“We pitted at the wrong time and the drive-through penalty certainly didn’t help. We made an error and there are no excuses for that,” he said.

“We win as a team and we lose as a team.”

Winterbottom might be more understanding for his partner’s error given the heroics that preceded it.

Canto leapt from 22nd on the grid to fourth place in the order by refusing wet tyres during the drizzle.

But one lap before he was due to hand over control to Winterbottom, Canto slipped off the racing line and into the fence.

“I was comfortable and the tyres were good. I hadn’t made a mistake until then,” Canto said.

Had the incident never happened and Winterbottom took fourth, he would have improved to third in the championship standings, just 122 points behind new leader van Gisbergen.

But Canto’s delayed exit from the mud and a long pit stop meant Winterbottom finished way back in 24th and 346 points in arrears.

“I feel for Mark, he was still racing for the championship,” Canto said.