Reports from the US claim the Brazilian suffered a heart attack while at The Concourse Club in Florida.
De Ferran was one of the greats of the CART era of US open-wheel racing, winning his first race for Hall/VDS Racing at Laguna Seca in his debut season in 1995 before challenging for the title with Walker Racing in 1997.
His big break came in 2000 when he signed with Penske Racing, winning the CART title that year, while also setting a closed-course land speed record at California Speedway with a 241.428 mph qualifying lap that stands to this day.
In 2005 he made his first steps into management, taking on the sporting director role at BAR-Honda.
He then set up his own team, de Ferran Motorsports, which competed in the American Le Mans Series.
He parted ways with the team in 2021 before returning this year in a consultancy role.
De Ferran also made a single Supercars start, with Tekno Autosport at the 2011 Gold Coast 600.
Close friend Tony Kanaan paid tribute to de Ferran on social media.
“Champion, friend, rival, mentor at the track and outside of it,” he wrote.
“I have no words to describe this loss. May you rest in peace my friend.”
Graham Rahal wrote: “So incredibly sad.
“Gil was such a tremendous guy, always a great person to get advice from and lean on. I couldn't be more devastated by this news. Prayers to the de Ferran family.”
Arrow McLaren also released a statement on Saturday morning Australian time.
“Everyone at McLaren Racing is shocked and deeply saddened to learn we have lost a beloved member of our McLaren family.
“We send our deepest condolences to Gil de Ferran's family, friends and loved ones.
“Gil was an important and integral part of our Racing team. He was a formidable force on and off track and made a lasting impact on everyone racing and working alongside him. He will be missed by everyone at McLaren Racing.”