He died Sunday at his home in Albuquerque, New Mexico, of natural causes, Indianapolis Motor Speedway said Monday.

Unser was one of the greatest racers in the history at the speedway, capturing the race in 1968, 1975 and 1981.

“He is part of the Mount Rushmore of Indy,” said Dario Franchitti, another three-time Indy 500 winner.

Younger brother Al Unser is one of only three drivers to win the Indy 500 four times — 1970, 1971, 1978 and 1987. The Unser family tradition stretched to Al Unser’s son, Al Unser Jr., who won the Indy 500 in 1992 and 1994.

“Bobby was a ferocious competitor on the track, and his larger-than-life personality made him one of the most beloved and unique racers we have ever seen,” said Roger Penske, the current speedway owner but the team owner for Unser’s winning car at the 1981 Indy 500.

“Beyond his many wins and accomplishments, Bobby was a true racer that raised the performance of everyone around him. He was also one of the most colorful characters in motorsports.”

Bobby Unser was born Feb. 20, 1934, in Colorado Springs, Colorado, and moved with his family as a child to New Mexico. His father owned a garage along Route 66 and he his three brothers grew up tooling around in old jalopies before he quit high school at 15 and began his racing career at Roswell New Mexico Speedway.

After two years in the U.S. Air Force from 1953 to 1955 — a stint in which he took pride — Unser turned to racing full time in what became a mighty career.

He was one of just 10 drivers to win the 500 at least three times, and Unser and Rick Mears are the only drivers to win the 500 in three different decades. Unser was one of six members of the Unser family to race in the Indianapolis 500.

Franchitti spent time each year at the speedway or at dinner with other past winners and said Unser was “always the largest personality in pretty much any room.”

“He showed up at the speedway and regardless of when he last raced, he still understood the race and what it took to win the race and he was still so very insightful,” Franchitti said. “He loved the Indy 500 so much. He loved coming back.”

Unser’s final Indy 500 victory in 1981 came in a Penske entry in one of the most contentious outcomes. Unser won from the pole and beat Mario Andretti by 5.18 seconds, but officials ruled Unser passed cars illegally while exiting the pit lane under caution — drawing a penalty that docked him one position and moved Andretti to winner.

Penske and Unser appealed and after a lengthy process the penalty was rescinded in October of that year. It was the 35th and final victory of Unser’s career.

At Indianapolis, Unser produced 10 top-10 finishes in 19 career starts. He led led in 10 races for a total of 440 laps, which to this day ranks 10th on the all-time list. He won two poles, in 1972 and 1981, and had nine front-row starts.

“When you mention icons in racing, and particularly the Indianapolis Motor Speedway, Bobby Unser was a legend,” said Doug Boles, president of the speedway. “He could drive, and win, in any type of car and on any type of track. And he was magical at Indy.”

After his driving career, Unser moved to a 20-year broadcasting career and won an Emmy Award as part of the ABC Sports broadcast team for “Outstanding Live Sports Special” for its coverage of the 1989 Indianapolis 500.

He was in the booth in 1987 when he called brother Al’s record-tying fourth 500 victory, and again in 1992 when nephew Al Unser Jr. won Indy for the first time in the closest 500 finish. When his TV career ended, Unser continued to visit the speedway every May. He was a driver coach who assisted on race strategy in 1998 and 1999 when son Robby Unser finished fifth and eighth.

Unser is survived by his wife, Lisa; sons Bobby Jr. and Robby; and daughters Cindy and Jeri.

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