Shelby died at Baylor Hospital in Dallas, according to an announcement by his company, Carroll Shelby Licensing. A cause was not disclosed.
He led a colorful, outsized life that touched virtually every corner of the automotive world, said Leslie Kendall, curator of the Petersen Automotive Museum in Los Angeles.
"He was the only individual to influence the designs of all three major American automakers. Everything he touched became legendary," Kendall said. "Even recently he was working on an experimental engine."
Living in the fast lane was a matter of fact for Carroll Shelby, who designed the cult-classic Shelby Cobras and Ford's Shelby Mustang.
He raced cars. He had a heart transplant from a Las Vegas gambler in 1990 and a kidney transplant from a son in 1996. He was married seven times.
While trying to fend off an anticipated heart attack, he drove in a 200-mile race in 1960 with nitroglycerin pills underneath his tongue, finishing third at Laguna Seca Raceway in Monterey.
"If I hadn't slowed down each time I popped one of those pills, I might have won," he said. He announced his retirement as a driver later that year after clinching the U.S. Road Racing championship series at Riverside International Raceway.
Five years earlier he had replaced a plastic cast on his broken elbow with a fiberglass one and had his hand taped to the steering wheel so he could help Phil Hill drive a Ferrari to second place in a 12-hour race at Sebring, Fla.
"Carroll Shelby is one of the most recognized names in performance car history, and he's been successful at everything he's done," said Edsel B. Ford II, a member of the board of directors of Ford Motor Co.and great-grandson of Henry Ford, founder of the company. "Whether helping Ford dominate the 1960s racing scene, to building some of the most famous Mustangs, his enthusiasm and passion for great automobiles over six decades has truly inspired everyone who worked with him."
Shelby most recently collaborated with the automaker on the 2013 Ford Shelby GT500 Mustang, which has 650 horsepower, making it the most powerful production V8 in the world.
Born Jan. 11, 1923, in Leesburg, Texas, Carroll Hall Shelby grew up in east Texas and attended high school in Dallas. He served as a flight instructor at Lackland Air Force Base near San Antonio during World War II.
Although he did not become a race driver until he was 29, his rapid successes and unique bib-overalls racing uniform made him a legendary figure before he retired at 37.
His first race, in January 1952, was in a drag race in a friend's MG. Later that year, he drove the same car in an oval track race in Norman, Okla., and won.
That's about the time the bib overalls became part of his lore.
"I was back home in Texas working on a chicken farm when I remembered I was supposed to be at a race at the Eagle Mountain Naval Air Station," he recalled. "It was real hot, so I didn't bother to change. The overalls were comfortable, so when I got to the track I kept them on. When I noticed how much attention they got, I decided to wear them all the time."
He first attracted international attention in 1954 in a Kimberly Cup race in Argentina where he drove an Allard with Dale Duncan. When the engine erupted in flames, Shelby instructed Duncan to douse the fire by urinating on it. The fire out, Shelby finished 10th, first among the amateur teams.
Returning home, he set a number of endurance records driving an Austin-Healey for Donald Healey at the Bonneville Salt Flats in Utah.
In 1957, he won 19 consecutive races and was named Sports Illustrated's driver of the year for the second time.