Marino Franchitti will join David Brabham and Simon Pagenaud in Highcroft Racing's American Le Mans Series line-up for the Sebring 12 Hours, Petit Le Mans and the ALMS round at Laguna Seca.
Franchitti, who drove for Dyson Racing in an LMP2 class Lola Mazda last season, will share the factory-backed Acura ARX-01c in the same races this year as his brother, IndyCar champion Dario, contested with the team last year.
"It's great to be joining the championship-winning team and linking up not only with last year's two fastest drivers in LMP1 in the ALMS, but also two good friends," said Franchitti.
"Brabs, I've known and admired for years and Simon became a friend almost from the time he came to the ALMS. I'm very excited about my role with the team because I will not only be doing the races at Sebring, Laguna and Petit Le Mans, but I'll also be attending all the other races in order to have a positive input into the development of the car.
"There are a lot of test miles planned for the championship defence so I know I won't be idle. Duncan [Dayton, team boss] has made no secret of his desire to contest the Le Mans 24 Hours and to expand the team to a second car, so there are some great opportunities ahead."
Franchitti, Brabham and Pagenaud will have their seat fittings next week and test the 2010 car for the first time the following week, ahead of the season-opening Sebring event on March 20.