The seven-time Supercars champion says the GT drive is a one-off having answered a call from Habul to take part in the event held from September 7-9.
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It will be only the 35-year-old's third non Supercars race contested outside of Australia having made appearances in two Race of Champions meetings.
“Kenny sent me an email and I thought ‘gee, this might be a good one to do', so I put my hand up,” Whincup told the official Supercars Championship website.
“I've got no plans, there's nothing more to it than it came up as the right thing at the right time and I grabbed it with two hands.
“I've never been to Laguna Seca. I've watched ChampCar there for many years, back when I was a kid and just really want to experience the Corkscrew, to be honest.
“The opportunity came up and I jumped at it. It should be good fun.”
The Triple Eight driver will conduct a pre-enduros Supercars test on September 4 before heading out to join up with Habul in California.