The 59th 500 Mile International Sweepstakes was held at the Indianapolis Motor Speedway in Speedway, Indiana on Sunday, May 25, 1975. A. J. Foyt started on the pole position and Bobby Unser won his second Indy 500.
On the 174th lap, a huge downpour pelted the Speedway, and officials immediately ended the race, just 26 laps short of the scheduled distance. Bobby Unser was leading the race at the red flag, and defending champion Johnny Rutherford was in second place. Pole-sitter A. J. Foyt came home third.
Dan Gurney, one of the founders of All American Racers, who finished second as a driver himself in 1968–69, won his first and only Indy 500 as an owner. Gurney's Eagle chassis itself scored its third "500" win.
Tom Sneva survived a spectacular crash in turn two on lap 125. His car touched wheels with Eldon Rasmussen, and flipped into the catch fence near the Turn Two Suites. The engine on Sneva's car ripped off in a huge fire-flash, and the car came to rest upright with Sneva trapped in the cockpit. Sneva miraculously suffered only minor injuries, and walked away from the wreck with assistance from the safety crews.
On the morning of the race, the Indianapolis Motor Speedway was ceremoniously designated to the National Register of Historic Places. In addition, the Hulman family celebrated thirty years of ownership of the facility.
A year earlier (1974), the race was held in the wake of the energy crisis. USAC cut out a week of practice, and trimmed time trials from four days to two days, in order to reduce energy consumption. These changes were well-received by competitors and fans, and USAC decided to make the reduction of practice time permanent; however, time trials were restored back to four days for 1975 and beyond.
For the second year in a row, turbocharger "boost" levels were set at 80 inHG maximum. Once again, top speeds would be in the low to mid-190 mph range, and would not challenge the track record.
On Thursday May 8, Gordon Johncock showed himself as a favorite for the pole, completing a practice lap at 195.228 mph. Johncock consistently led the speed charts on four of the practice days. A. J. Foyt was close behind, topping the speed chart twice.
Pole day dawned sunny and mild. Rookie Al Loquasto was the first driver out to qualify. Mike Mosley (187.833 mph) led the speeds early on, and was the fastest car through the first hour. At 12:15 p.m., Tom Sneva (190.094 mph) moved into the top spot.
About an hour later, Bobby Unser took to the track, and at 191.073 mph, bumped Sneva off the pole spot. Unser's speed did not last long, as Gordon Johncock, the next car out, then took over the provisional pole at 191.652 mph. Johncock was the last car to complete a run during the early segment. The track remained mostly quiet over the next three hours, as drivers waited for cooler conditions.
Shortly after 4 p.m., A. J. Foyt blistered the track, with his first lap coming in at 195.313 mph. His four-lap average of 193.975 mph secured the pole position.
The final qualifying attempt of the afternoon was put in by Bill Puterbaugh. After six years of failure, Puterbaugh finally qualified for his first Indy 500. He pumped his fist as he returned to the pits, putting in the 15th-fastest speed of the day.
The day closed with the field filled to 22 cars.
After blowing his engine the day before, Wally Dallenbach returned to the track and qualified. His speed of 190.646 mph was the 4th-fastest overall, but as a second day qualifier, he would be forced to line up 21st.
A total of six cars qualified, and at the close of the first weekend of time trials, the field was filled to 28 cars.
With five spots open in the field, qualifying opened with Mike Hiss the first car to make an attempt. The field was quickly filled to 33 cars, and Lee Kunzman was the first car on the bubble.
Mario Andretti returned from Monaco, and put his car solidly in the field with a speed of 186.480 mph, easily the fastest driver of the day, bumping Kunzman in the process. At 12:18 p.m., Al Loquasto was now on the bubble.
Billy Scott made two attempts to bump his way in, but blew his engine on the first attempt, and waved off the second. No other cars made an attempt the rest of the day.
On the final day of time trials, Al Loquasto still clung the bubble spot. Eldon Rasmussen was the first car out to make an attempt. His first lap was over 183 mph, but the next two dropped off and the team waved off the run. Three hours later Jim Hurtubise blew an engine after one slow lap, and Loquasto was still on the bubble after over 24 hours.
With about an hour left in the day, Loquasto survived two more attempts. At 5:18 p.m., just under 42 minutes left in the day, Eldon Rasmussen made his second attempt. His speed of 181.910 mph bumped Loquasto and the field would be set.
Loquasto, the first driver to complete a qualifying attempt on pole day, was the last driver to be bumped on bump day.
Gordon Johncock took the lead at the start and led the first 8 laps. But Johncock dropped out on lap 11 with an ignition failure. Also out early were Salt Walther (his Indy record third last place finish), and Lloyd Ruby, both out with engine problems.
Polesitter A. J. Foyt took the lead on lap 9. He briefly lost the lead for three laps during a pit stop on lap 22, but re-assumed the lead on lap 25, and led through lap 58. Salt Walther, who had dropped out, summoned his teammate Bob Harkey to the pits on lap 18. Walther climbed in the car and took over the machine for the remainder of the race. While the driver switch was apparently agreed upon before the race if the circumstances arose, Walther was criticized for making the switch under green, and not waiting for a caution period. The Harkey/Walther car fell a few laps down during the stop.
The first yellow came out on lap 45 for Mike Hiss, who went high and brushed the wall in turn three.
During his first scheduled pit stop, Mario Andretti's car stalled several times trying to leave the pit lane. He lost several laps, but eventually rejoined the race. On the leaders' lap 68, Andretti spun out on the backstretch, and slammed into the inside wall near the entrance to turn three. He was out of the race after completing only 49 laps.
Wally Dallenbach took the lead for the first time on lap 59. He would lead a total of 96 laps, giving up the lead only during pit stops.
NASCAR regular Bobby Allison managed to lead one lap during a pit stop shuffle, in what would be his final start at Indy. Allison had decided to skip the World 600 at Charlotte and was the final noteworthy "cross over" driver to the Indy 500 during that era.
On the 73rd lap, A. J. Foyt passed Cliff Bergere (2,425) for first place all-time in total laps completed at the Indy 500.
During a sequence of green flag pit stops, A. J. Foyt appeared to run out of fuel going into turn 1. Coasting down the backstretch, seemingly without power, it appeared that Foyt was fiddling with his headrest or something behind the cockpit. Seconds later, he was back up to speed, and made it to the pits for fuel.
On lap 125, Tom Sneva approached the lapped car of Eldon Rasmussen in turn 1. As the two cars went side-by-side in turn two, they touched wheels and Sneva's car flipped up into a huge wreck. Sneva did a barrel-roll over the front nose of Rasmussen's car, becoming completely airborne and upside-down. The car rolled upright, and hit the outside wall and catch fence with the back end. The engine, gearbox, and rear of the car were ripped from the chassis, leaving a huge fire flash as the fuel and oil ignited in front of the Turn Two Suites. The cockpit section continued down the track, flipping at least twice, and came to rest on the track, right side up, then spun for several yards, coming to rest facing backwards. The engine and other parts scattered in different directions, and littered the track with debris.
Sneva was conscious when the car came to rest, and immediately started unbuckling his seat belts trying to get out. The back of the car was still on fire, and he unknowingly lifted his visor, which singed his face with burns. He then put his hand down in a pool of methanol, which burned his fingers. His legs were trapped in the cockpit, and he was not able to get out of the car on his own. Rescue workers immediately arrived at the scene, and put out the remaining fires. A moment later, he was pulled from the wreck, and with assistance, walked to the ambulance.
Sneva did not suffer any serious bodily injuries, but was listed in serious condition with burns to his face and hands. After a couple days, Sneva's condition was quickly upgraded, and after a month, he was back racing.
After leading 96 laps, Wally Dallenbach dropped out with a blown piston on lap 162. That handed the lead to Johnny Rutherford, with Bobby Unser now in second.
Bobby Unser took the lead on lap 165. The skies were threatening, and rain was expected to move into the vicinity of the Speedway.
On lap 170, Gary Bettenhausen's right rear hub exploded and he lost the wheel down the mainstretch. Precariously riding on three wheels, he skillfully managed to keep the car mostly off the wall, and was able to park the car down in the infield of turn one. The caution light came on for the debris, and leader Bobby Unser ducked into the pits for a quick stop (fuel only). Second place Johnny Rutherford also made a pit stop. A minor fire broke out in Dick Simon's pit, but it was quickly doused.
Under the yellow, the skies became increasingly dark, and the rain that had been threatening finally was about to arrive.
Bobby Unser suddenly ducked into the pits for a second "splash-and-go" pit stop, topping off the tank in just 6 seconds. He came out to the track alongside third place A. J. Foyt, who at that instant managed to un-lap himself. One lap later, the skies opened up, and it began to pour rain. It was lap 174 and Bobby Unser was leading, with Johnny Rutherford about a half lap behind in second. The track became flooded and many of the cars began hydroplaning and spinning out of control. The visibility dropped to near zero, as the heavy rain and the "rooster tails" made it difficult for the drivers to see. Fans began scurrying for cover.
Starter Pat Vidan immediately took out the red and checkered flag, and USAC officials immediately halted the race. The leaders had to precariously coast around to the finish line. Despite several wrecked cars blocking the track, Unser, Rutherford, and Foyt all managed to make it to the finish line cleanly. The race was officially called with Unser completing 174 laps (435 miles), just 26 laps short of the scheduled distance. Defending champion Johnny Rutherford followed with a second place, and pole-sitter Foyt finished third, still looking for the elusive fourth Indy win.First alternate: Rick Muther (#46, #52) – Bumped
Second alternate: Al Loquasto (R) (#38, #86) – Bumped
Lee Kunzman (#52, #55) – Bumped
Jim Hurtubise (#52, #56) – Wave off
Tom Bigelow (#17) – Wave off
Graham McRae (#75) – Wave off
Billy Scott (R) (#76) – Wave off
Jan Opperman (#28, #46) – Incomplete run
Larry Cannon (#59) – Wrecked in practice
Chuck Gurney (R) (#23) – Wrecked in practice
Jigger Sirois (R) (#52) – Wrecked in practice
Jerry Sneva (R) (#37, #38) – Wrecked in practice
George Follmer (#28, #52) – Blew engine in practice
John Hubbard (R) (#53)
Dan Murphy (R) (#25)
Bob Nagel (R)
Bill Simpson (#52, #98)
Race stopped on lap 174 due to rain (begun on lap 171).
This was the final race for Mary Catherine "Mom" Unser (mother of Jerry, Bobby, and Al), a fixture in the garage area who was famous for her spicy chili. She died on December 17, 1975.
Jimmy Caruthers was diagnosed with cancer in late 1974, but after treatment went into remission, was able to return to the cockpit for the 1975 race. He finished 14th, but eventually succumb and died on October 26, five months after the race.
The race was carried live on the IMS Radio Network. Sid Collins served as chief announcer. The broadcast crew was largely familiar from 1974. The broadcast was carried on 1,200 affiliates including shortwave transmissions via AFN to Europe, Asia, Thailand, and many other locales. It was heard by over 100 million listeners worldwide. Collins had no celebrity guests in the booth during the race. But during the pre-race coverage, Collins interviewed Senator Barry Goldwater as well as Pete DePaolo, who was celebrating fifty years since his victory in 1925.
The race was carried in the United States on ABC Sports on a same-day tape delay basis. Jim McKay sat out the broadcast due to a bad cold, and was replaced by announcer Keith Jackson, who had been scheduled to report from the pits that day. Jackie Stewart returned to serve as analyst after missing the 1974 race. Sam Posey, who served as analyst in 1974, was moved to the pit area.
The broadcast has re-aired on ESPN Classic since May 2011.