Garth Tander sweeps V8s Clipsal 500 races

Championship leader Jamie Whincup's team launched a blistering attack on V8 Supercar rules after stewards punished him for a safety problem that resolved itself.

Whincup was controversially black-flagged in a thrilling race at Adelaide's Clipsal 500 with just eight laps remaining as he looked set to extend his championship lead.

Sitting second behind Holden rival and eventual winner Garth Tander, Whincup was penalised by stewards after his car's rear bumper was left dangling because of a nudge from Ford driver James Courtney.

Officials hung out the black flag ordering Whincup to pit but soon afterwards the errant bumper was knocked off and fell clear of the racing line.

Stewards still demanded Whincup pit for a drive-through penalty - infuriating Team Vodafone boss Roland Dane as his defending champion slid to an 18th-place finish.

"It's absolute nonsense, I've never seen anything so stupid in my life," Dane said.

"We made the sport look ridiculous in front of all these people and all the viewers at home.

"You can see the offending article's come off the car and you're called in when you know perfectly well there's nothing wrong with it.

"There's nothing to be achieved ... it's pretty dumb.

"If the part had come off straight away, there'd have been no question of a black flag. Why does the situation suddenly change because of the timing of when it comes off?"

Whincup, who won the opening four races of the season in the Middle East, would have extended his championship lead to over 150 points if he had finished on the podium.

Instead his buffer was slashed to a mere 57 points over second-placed Mark Winterbottom, who finished third to Tander and Courtney in Sunday's race.

Tander, who won Saturday's opening race, eventually prevailed in a thrilling final few laps of the 250km event.

The Holden Racing Team driver rode a daring strategy of not refuelling late in the race.

He squeaked home with barely any fuel in the tank while having to deal with a late charge from Courtney and some nervous sliding on a track left slightly damp from rain.

Tander is now eligible for a $2 million bonus for any driver who can sweep the sport's Grand Slam - Adelaide, Bathurst, Gold Coast and Sydney.

More than 89,000 fans attended Sunday's race, bringing attendance for the four-day event to nearly 280,000.

- AAP