He drove for Briggs Cunningham and John Mecom. Hansgen won the Formula Junior race at the inaugural United States Grand Prix meeting at Sebring, Florida, on December 12, 1959, driving a Stanguellini. Hansgen won the Monterey Grand Prix, at Laguna Seca Raceway, on October 17, 1965, driving John Mecom's Lola T70-Ford. He participated in several races of the 24 Hours of Daytona and Le Mans as well as the 12 Hours of Sebring endurance races. He also was notable for introducing Mark Donohue to professional road racing.