Dec 10 (Reuters) - Al Unser, who was part of one of American motor racing"s most famous families and one of only four drivers to win the Indianapolis 500 four times, has died at the age of 82 after a long illness. Unser, who was diagnosed with cancer 17 years ago, died on Thursday at his home in Chama, New Mexico, the Indianapolis Motor Speedway said on Friday. "His quiet and humble approach outside of the car, combined with his fierce competitive spirit and fearless talent behind the wheel, made Al a fan favorite," Indianapolis Motor Speedway President J. Douglas Boles said in a statement. "He will be remembered as one of the best to ever race at Indianapolis, and we will all miss his smile, sense of humor and his warm, approachable personality." Despite being known for his patience behind the wheel, Unser holds the record for the most laps led in the Indianapolis 500, having pushed the all-time mark to 644. With 27 starts in the race, he trails only A.J. Foyt (35) and Mario Andretti (29). Unser won the Indianapolis 500 in 1970, 1971, 1978 and 1987 while older brother Bobby Unser, who died in May, triumphed in 1968, 1975 and 1981. They are the only brothers to win the race. In 1992, Unser finished third in the Indianapolis 500 on the same day 30-year-old son Al Unser Jr. took the chequered flag, making them the only father and son to win the race. Unser Jr. pushed the family"s total of victories at the International Motor Speedway to nine when he won again in 1994. "We have lost a true racing legend and a champion on and off the track," said Indianapolis Motor Speedway owner Roger Penske. "Al was the quiet leader of the Unser family, a tremendous competitor and one of the greatest drivers to ever race at the Indianapolis Motor Speedway." Unser picked up his first Indianapolis 500 win in dominant fashion as he led 190 of the 200 laps from pole and beat runner-up Mark Donohue by 32.19 seconds. By the time of his retirement, Unser had collected 39 IndyCar wins, which is sixth on the all-time list, and season championships in 1970, 1983 and 1985. "I feel loss & sadness at the passing of Al Unser," motor racing great Andretti, who along with Unser was part of the decorated 1965 IndyCar rookie class, wrote on Twitter. "One of the top 5 racers who has ever lived - and the kindest, calmest, smartest, toughest, most fun, well-liked guy ever."