Bobby Unser, a three-time winner of the Indianapolis 500 and member of one of the most storied families in American racing, who achieved glory in three separate decades while employing an aggressive, hard-charging strategy on the track, died May 2 at his home in Albuquerque. He was 87.

His death was announced by Indianapolis Motor Speedway, which did not give a specific cause. He and his younger brother, Al, a four-time champion at the Brickyard, were the only pair of siblings to win the Indy 500.

Mr. Unser raced with a simple philosophy in mind: “Go fast, lead and win.” A self-described “charger,” he drove jalopies as a boy, started racing at Speedway Park in Albuquerque at age 15 and later broke the 170 mph barrier at the Indy 500, where he notched victories in 1968, 1975 and 1981.

While competing against rivals such as Mario Andretti and A.J. Foyt, he sought to train his subconscious before each race by visualizing the course as well as the state of his car, down to the air pressure of the tires. He was one of only 10 drivers to win the Indy 500 three times — he led 440 laps in all, ranking 10th all-time — and won 35 Indy car races before retiring as a driver in 1982.

Mr. Unser, who also won sprint, stock and midget car races, came from a family steeped in racing and closely associated with the Pikes Peak International Hill Climb in Colorado. His father and uncles were masters of the race, which runs more than 12 miles and boasts 156 turns, ascending to an elevation of 14,115 feet.

Following his uncle Louis Unser, a nine-time champion, Mr. Unser won 13 times at Pikes Peak, cannonballing up the two-lane road in open-wheeled, stock and sports cars. He boasted he could draw a map of the course by memory, identifying curves with such names as Devil’s Corner and Bottomless Pit, and was the first to break the 14-, 13- and 12-minute marks on the mountain.

“I’ll tell the guys [starting] in front of me, ‘If you have a problem, watch your mirror, ’cause I’ve got no time to screw with you when I catch you,’ ” he told the St. Petersburg Times in 2001. “That’s a terrible thing to say, I know, but it’s a part of life. I hate to say it, but I’m a professional hit man during the race. I’m not there to have coffee with the guy.”

Mr. Unser said he scarcely feared accidents and collisions, although an uncle was killed on the track and an older brother, Jerry Unser Jr., died in a crash while practicing for the 1959 Indy 500. Accidents were simply a fact of life, he said; his chief fear instead was heights, which he said he confronted by learning to fly twin-engine planes.

“Luck is everything,” he told the New York Times in 1975. “If you don’t have luck on the racetrack, you can’t win. Luck controls everything in our lives. I’ve always tried to have it on my side.”

At Indy, he was perhaps best known for his 1981 battle with Andretti, whom he beat by 5.18 seconds while driving a Penske-Cosworth. A day later, race officials ruled that Mr. Unser had illegally passed several cars while exiting the pit lane during a caution. They penalized him one lap, handing the victory to Andretti.

After an appeal process that stretched more than four months, the penalty was changed to a $40,000 fine. Mr. Unser was hunting elk in New Mexico when he received a radio message from his wife at the time, Marsha Unser, who explained that he had been named the new champion. “That’s the first time I could remember he was totally quiet for four or five seconds,” she later told the Times. “Stunned disbelief was his reaction.”

The episode left him disillusioned with racing, convinced that the initial penalty had tarnished his legacy; it also gave him an ulcer and led him to start taking the anti-anxiety medicine Valium. “I’ve got to change my life some way,” he told Sports Illustrated in 1982, before announcing his retirement.

“I have no slow days in my life,” he added. “There is no such thing as a slow day in the life of Bobby Unser. I was trained to go fast, and I will go fast until the day I die.”

The third of four sons, Robert William Unser was born in Colorado Springs on Feb. 20, 1934, and grew up in Albuquerque. His mother was a schoolteacher, and his father ran a garage along Route 66, where he trained his sons to maintain their own cars. By age 9, Mr. Unser was driving a Model A Ford on dirt roads through the desert.

At 17, he competed in the Carrera Panamericana, a more than 1,900-mile race across Mexico. His father navigated their Jaguar sedan, and they narrowly survived an accident that killed another driver before crashing into a wall in a village square while leading the race, according to Sports Illustrated.

Mr. Unser dropped out of high school, raced at night while serving in the Air Force and debuted at Pikes Peak in 1955, winning his first championship there the next year.

He had a slower start at the Indy 500, where in his 1963 debut he completed only two laps, finishing last after crashing his turbocharged Kurtis-Novi. He finished only one lap the next year, coming in second to last after getting caught in a seven-car accident that killed two drivers, Dave MacDonald and Eddie Sachs.

In his 1968 victory, he drove an Eagle-Offenhauser in a duel with Joe Leonard, whose fuel pump drive shaft broke on lap 192 of 200. Mr. Unser won his first U.S. Auto Club national championship later that year. He won his second national title in 1974, after finishing second to Johnny Rutherford in the Indy 500.

Mr. Unser had by then established himself as one of the fastest men in racing, winning his first Indy 500 pole position in 1972 after qualifying with a record four-lap average speed of 195.94 mph — more than 17 mph faster than the record Peter Revson set the previous year. In 1975, he was trailing for most of the Indy 500 but moved ahead of Rutherford on lap 165, then held on until the race was cut short by a sudden rainstorm after 174 laps.

In the 1980s and ’90s, Mr. Unser worked as a race analyst and covered the Indy 500 as a color commentator for ABC. He was in the booth in 1987 when his brother Al became the second four-time winner; in 1989, as a member of a broadcasting team that earned an Emmy Award for live sports coverage; and in 1992 when his nephew Al Unser Jr. won his first of two Indy 500 titles.

Mr. Unser continued racing even after he retired from Indy cars, returning to Pikes Peak in 1986 to win his final title on the mountain. When his son Robby raced in the 1998 and 1999 Indy 500s, finishing fifth and eighth, respectively, Mr. Unser served as a driver coach. He also joined Robby at Pikes Peak, giving advice on the road. “That fixes my need. I’m still a race driver,” he told the Los Angeles Times.

His marriages to Barbara Schumaker, Norma Davis and Marsha Sale ended in divorce. Survivors include his wife of 21 years, Lisa Unser; two children from his first marriage, Bobby Unser Jr. and Cindy Unser; two children from his second marriage, Robby and Jeri Unser; his brother Al Unser; and four grandchildren.

Mr. Unser was inducted into the Indianapolis Motor Speedway and International Motorsports halls of fame in 1990, and the Motorsports Hall of Fame of America in 1994.

“Balance is important, but I’ve lived my life the opposite. I must go fast,” he told USA Today in 2004. “Winning will happen. Go fast in practice, go fast in qualifications, lead the race rather than be conservative. Go down in style. More people will remember you.”

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