The 56th 500 Mile International Sweepstakes was held at the Indianapolis Motor Speedway in Speedway, Indiana, on Saturday, May 27, 1972. The race is notable in that for the first time, the cars were permitted bolt-on wings, and speeds climbed dramatically. Bobby Unser won the pole position with a four-lap average speed of , breaking Peter Revson's track record from 1971 by over 17 mph – the largest one-year track record increase in Indy history. The race average speed of was also a new record, which stood until 1984.

Gary Bettenhausen led 138 laps (of 200) until his car suffered ignition trouble on lap 176. He coasted to the pits and wound up 14th. Jerry Grant took over the lead, but pitted for a new tire and fuel on lap 188 in teammate Bobby Unser's pit – for which he was later disqualified. Bettenhausen's Penske teammate Mark Donohue won the race, after leading only the final 13 laps. It was car owner Roger Penske's first of twenty Indy 500 victories (as of 2026) and the first victory for a McLaren chassis at Indy. Al Unser Sr., who won the race in 1970–1971, was looking to become the first driver in history to "three-peat" at the Indianapolis 500. He fell short, but his runner-up finish ties for the best three-year span (1st–1st–2nd) in Indy history.

For the first time, Jim Nabors was invited to sing "Back Home Again in Indiana" during the pre-race ceremonies. Nabors accepted and performed with little rehearsal and was warmly received. It was the beginning of a 36-year tradition, where Nabors performed nearly every year from 1972 through 2014.

The 1972 race was the first to utilize the Electro-PACER Light system to facilitate the yellow light caution periods. Speedway officials still did not utilize the pace car during cautions, and this enforcement tool would be used at Indy for seven years, albeit not without controversy in subsequent races. This system was similar in concept to the Virtual Safety Car and the "Slow zone" that became popular in the 2010s. However, the technology for the PACER system was primitive compared to the later systems used decades later, and proved difficult to enforce.

After the decade of the 1960s saw numerous drivers from Europe and other nationalities, the 1972 race was the first since 1962 and the most-recent to have an all-American lineup. Mario Andretti who was born in Istria (part of Italy at the time) was the only foreign-born driver, however he was a naturalized U.S. citizen at the time of this race.

Race schedule Following the pattern set in 1970 and 1971, the race was scheduled for the Saturday of Memorial Day weekend. This would be the final Indy 500 scheduled for a Saturday (the 1986 race was held on a Saturday due to a week-long rain delay). Falling on May 27, it was also the earliest calendar date that race had been held up to that point. In 1973, the race would be scheduled for Monday, and starting in 1974, the race would permanently move to the Sunday of Memorial Day weekend.

On Sunday May 28, the annual 500 Victory Banquet was held at the newly completed Indiana Convention Center for the first time.

Race schedule — April/May, 1972SunMonTueWedThuFriSat23 24 25 26 27 28 29Practice30Practice 1Practice 2Practice 3Practice 4Practice 5Practice 6Practice 7Practice 8Practice 9Practice10Practice11Practice12Practice13Pole Day14Time Trials15Practice16Practice17Practice18Practice19Practice20Time Trials21Bump Day22 23 24Carb Day25 26Parade27Indy 50028 29Memorial Day30 31     Color Notes Green Practice Dark Blue Time trials Silver Race day Red Rained out* Blank No track activity * Includes days where trackactivity was significantlylimited due to rain

Practice and time trials In 1972, for the first time, USAC allowed bolt-on wings to be affixed the cars. Previously, "wings" were required to be integral parts of the car's bodywork. Downforce levels increased by significant margins, and speeds climbed substantially during practice. During a tire test in March, Bobby Unser reportedly drove a lap of 190.8 mph, the first driver ever to lap the Speedway unofficially at over 190 mph.

The existing official track record going into the month had been set by Peter Revson in 1971 at 179.354 mph. During the first week of practice, the stage was set for record speeds early on. During the first day the track was available, Sunday April 30, Jim Malloy became the first driver to break the 180 mph barrier in practice, at 181.415 mph. Later in the week, Malloy ran a practice lap of 188.048 mph, by far an unofficial track record. By the end of the first week of practice, 11 drivers had practiced over 180 mph.

During the second week of practice, Gary Bettenhausen turned a lap of 190.315 mph on Sunday May 7. He became the first driver ever of the month to break 190 mph. Two days later, Bettenhausen was over 191 mph. Not to be upstaged, on Wednesday May 10, Bobby Unser blistered the track at 194.721 mph.

By the eve of pole day, three drivers had cracked the 190 mph barrier in practice, and more than a dozen had practiced faster than the existing qualifying record.

First day time trials – Saturday May 13 Pole day time trials were scheduled for Saturday May 13, however, rain kept the track closed most of the day. The track opened briefly for practice, and at 5:50 p.m. time trials began. Three cars made it on the track, but none of them completed runs. A. J. Foyt was the last car out, but he blew his engine in turn two right after taking the green flag.

Second day time trials – Sunday May 14 Pole qualifying was moved into Sunday, and the qualifying line picked up where it had left off the day before. The track opened for practice promptly at 9 a.m. At 10:21 a.m., Jim Malloy slid high exiting turn 3, and hit the outside wall in the north short chute. He suffered fractured arms and legs, burns, and was in critical condition. Four days later, Malloy would die from his injuries.

After the Malloy crash, rain closed the track until 2:30 p.m. Bill Vukovich II was the first driver to make a qualifying attempt. His first lap of 185.797 mph was a new one-lap track record, and the first official lap at Indy over 180 mph. However, he did a 360° spin in turn one, and came to rest against the outside wall on the second lap, and the run was for naught. Mike Mosley went out next, but the car quit on the final lap. More rain fell, and the track closed for another hour to wait out the shower.

At 4:15 p.m., Joe Leonard (185.223 mph) became the first driver to complete a qualifying run. He set one and four-lap records, but they would not last long. Mario Andretti (187.617 mph) was the next car out, and he took over the top spot temporarily, also breaking the track record in the process.

Shortly before 5 p.m., Bobby Unser took to the track. He set new all-time one and four-lap qualifying records, becoming the first driver to officially break the 190 mph barrier at Indianapolis.

Lap 1 – 46.17 seconds, 194.932 mph (new 1-lap track record) Lap 2 – 45.91 seconds, 196.036 mph (new 1-lap track record) Lap 3 – 45.76 seconds, 196.678 mph (new 1-lap track record) Lap 4 – 45.89 seconds, 196.121 mph Total – 3:03.73, 195.940 mph (new 4-lap track record)

Unser established himself as the man to beat for the pole position. He shattered the previous year's track record by over 17 mph. Twelve cars completed runs and the 6 o'clock gun closed the track with six cars still left in line. The pole position round would be stretched into the following weekend. Among those not yet on the track were Mark Donohue and Peter Revson. After blowing his engine Saturday, A. J. Foyt was ineligible for the pole, and was not yet in the field either.

Third Day – Saturday May 20 Six cars entered the day still eligible for the pole round, and five of those made attempts. Mark Donohue put himself on the front row with a run of 191.408 mph. Moments later, Peter Revson put himself second with a run of 192.885 mph. Bobby Unser held on to the pole position, and the front of the field was set. For the first time since 1940–1941, the same three drivers qualified on the front row in consecutive years. Unser, Revson, and Donohue started on the front row (albeit in different order) in 1971 as well.

At 11:30 a.m., "third day" qualifying commenced. A. J. Foyt put his car solidly in the field with 188.996 mph. Two-time defending race winner Al Unser, Sr. also qualified. The fastest of the "third day" qualifiers would be Jerry Grant, with a run of 189.294 mph.

At the end of the day, the field was filled to 27 cars.

Bump Day – Sunday May 21 (Jim Hurtubise "Beer engine")

After blowing five engines during the month, Gordon Johncock finally put a car in the field. His speed of 188.511 mph would be the fastest of the day (8th-fastest overall), and he qualified in 26th.

At 5 p.m., Salt Walther filled the field to 33 cars. Wally Dallenbach (178.423 mph) was now on the bubble. Dallenbach survived three attempts, but was eventually bumped by Cale Yarborough with a half-hour remaining. Yarborough (178.864 mph) beat Dallenbach's time by a mere 0.50 seconds, however, Yarborough himself was now on the bubble. An agonizing final 25 minutes saw six drivers try to bump him out. One by one, they each fell short. Seconds before the 6 o'clock gun, Wally Dallenbach got in a back-up car for one last chance. His first two laps were just shy of bumping in, and on his third lap, the car began smoking. He was forced to pull into the pits and wave off the run. The field was set with Yarborough holding on to make the field. All 33 cars in the field qualified faster than the pole car from the previous year.

As the attention on the track was focusing on Cale Yarborough, Jim Hurtubise wheeled front-engined Mallard roadster in to the qualifying line shortly before the closing deadline of 6 p.m. The car was sponsored by Gohr Distributing, a Buffalo-area beer distributor for various brands of beer, and they promoted the Miller High Life brand on the car.

Since Hurtubise had already qualified himself, when asked why he was putting the car in line, he claimed he 'might put someone else in it,'The Talk of Gasoline Alley – 1070-AM WIBC, May 19, 2007 a practice that was commonplace at the time. Hurtubise had become known for last-minute (unsuccessful) qualifying efforts in his obsolete front-engined roadster, usually to the delight of fans, but sometimes drawing the ire of others.The Talk of Gasoline Alley – 1070-AM WIBC, May 17, 2003 Time expired before the Mallard got anywhere near the front of the line. In fact, Hurtubise queued the car late on purpose, as he did not want it to make it to the front. With qualifying officially concluded, the engine cover was removed to reveal that car had no engine. Instead it had a plastic-lined trough filled with ice and a number of chilled bottles of his sponsor's product, which he shared with the other pit crews and race officials.

Many in attendance found the gesture humorous, however, some officials were not amused. Some had even become skeptical before he opened the cover, as melting ice was already creating a pool of water underneath the car. It was the first of several run-ins Hurtubise would have with USAC officials, and prompted rule changes to prevent another such ruse. (In modern times, alcohol is prohibited in the pit area owing to WADA Code that prohibits alcohol among participants in motorsport events.)

As a result, cars are now subject to cursory inspection, even before arriving at the official technical inspection area, and must obtain a sticker from officials to notify officials the car has been approved before entering the qualifying line.

Carburetion Day