Helio Castroneves switches from IndyCar to IMSA with Penske for 2018

Penske had already confirmed Juan Pablo Montoya and Dane Cameron in one of its two new Acura DPi cars, but it postponed talks with Castroneves until after this year's IndyCar season was over.

However, Castroneves was testing the Acura at Sebring the day after the IndyCar finale in Sonoma, and he will join Montoya and Simon Pagenaud in this weekend's Petit Le Mans at Road Atlanta campaigning a Penske-entered ORECA-Gibson.

"Helio has been a valuable member of Team Penske for almost 20 years,and we are looking forward to sharing more success together," said team owner Roger Penske.

"Competitors like Helio, Rick Mears and Mark Donohue are what have made Team Penske what it is today.

"This represents a new challenge for him and I know he is excited about the opportunity.

"Having established winning drivers like Helio and Juan teaming up with young and talented racers that know the series like Dane Cameron, will help give our new sportscar program a solid foundation as we head into the 2018 season."

Castroneves spent 20 seasons in IndyCar, the first two with Bettenhausen Racing and Hogan Racing, and then 18 with Penske - and he will contest the Indy 500 with the team next year alongside his IMSA deal.

In that time he took 30 wins, 50 pole positions, and finished inside the top five in the championship 14 times. His 30th win, scored at Iowa Speedway this season, meant he surpassed Mears as the team's most successful driver.

Castroneves has also made five starts for Penske in sportscars, producing two poles, three podium finishes and a class victory in the 2008 Petit Le Mans.

"I've been fortunate to achieve a lot of my personal goals with Penske over the years," said Castroneves, who famously never won the IndyCar championship.

"Helping Roger, the team and everyone with Acura start this program and build it from the ground up will be another big challenge and a great opportunity in my career.

"I am proud of everything we have accomplished together in IndyCar and now I am focused on helping to develop the ARX-05 to try and win the 24 Hours of Daytona and the IMSA championship in 2018 with Acura.

"I'm also excited to get a chance to race again for Team Penske at the Indianapolis 500.

"That race is near and dear to my heart and trying to become the fourth four-time winner is something I really want to accomplish in my career.

"We've come so close the last few years and with this team, I know we will have a great opportunity to try and make some history."