Leo and Greg Mansell are to continue their racing careers in America from 2008, where they will race for Champ Car Atlantic team Walker Racing.
The team who won the 2006 Atlantic title with Simon Pagenaud, tested Nigel Mansell's sons at Sebring last month, and a deal was quickly hammered out in time for the announcement today at the Los Angeles Auto Show.
Team owner Derrick Walker said: "I was very impressed with Greg and Leo at Sebring. They had such a professional approach, such desire to compete and win and most surprisingly they had consistency in tricky conditions.
"It was really hot and between them they clocked up 900 miles over the two days, they gave good feedback, they were making lots of changes and those changes were good ones. They're bright kids - proper thinking drivers."
Walker added that he expects the pair to pursue a long career in America now, rather than heading back to Europe after a stint in the Champ Car feeder series.
"I think Greg in particular is bullish about getting into Champ Car in 2009," he said, "although it may turn out to be a two-year Atlantic programme for him.
"But that's good to have that desire, and I'm just happy that Nigel and his sons seem so committed to the Champ Car organisation as a whole.
"I don't think they're going to be one-year wonders who then bugger off back to Europe. I think they want to really build up their careers over here."
Nigel Mansell, who won the Champ Car title in 1993, just a year after becoming Formula One world champion, commented: "What a tremendous challenge and adventure we will all have in 2008.
"It's a fantastic series revisiting some wonderful venues which will bring back such fond memories of when I raced in Champ Cars. This is a fantastic opportunity for Leo and Greg."
Greg, who finished 10th in the British Formula 3 championship this year said: "It is an incredible adventure. The Atlantic cars are very demanding to drive and the test at Sebring was a wonderful experience.
"Carrying so much speed in the corners suits my driving style and I am very excited about the forthcoming season. Working with Walker Racing is a major step up in professionalism."
Leo added: "For the first time ever I have been shocked at how a good car feels. The brakes, the handling and the aerodynamics of the car and the balance was the best I have ever driven and it gives me so much more confidence.
"The car is far more challenging than the Formula 3 cars, but because of the balance of the car and the professionalism of the team, I have so much more confidence in the car."
Walker Racing, which suffered a poor season in 2007 with Ryan Lewis and Simona de Silvestro, have pledged to strengthen their engineering line-up. "We've lost one guy since the Atlantic season ended, but we've put out ads and had responses from some really talented people," Walker said.
"Don't get me wrong, Greg and Leo will be on a steep learning curve and if, say, Frank Perera ['07 series runner-up] comes back to the series, he's going to be awfully strong. But I'm confident our guys are going to be running up at the front like we were in '06.
"It's a strong line-up. Kevin Lacroix has already run in the series for almost a complete season, has won a race, and obviously we're going to encourage a free-flow of information between all drivers and engineers."
As last year, the squad will run under the Walker Racing banner, rather than Team Australia, which Walker co-owns and runs with Craig Gore. As a result, Derrick has felt free to run the cars in British red, white and blue, rather than the 'mini-Team Australia' colours.
Walker's third Atlantic car will be piloted by Lacroix, who won his second ever Atlantic race at Portland last year.