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.
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.
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.
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.
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.
After blowing five engines during the month, Gordon Johncock finally put a car in the field, with a comfortable 188.511 mph.
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 bumped by Cale Yarborough with a half-hour remaining. Yarborough (178.864 mph) now found himself 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, and he was forced to pull into the pits. The field was set with Yarborough making 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 his Miller-sponsored Mallard in the qualifying line shortly before the closing deadline of 6 p.m. Hurtubise's sponsor was actually a Hamburg, New York beer distributor named Richard Hammond, with Miller High Life chosen as the brand to promote. 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,' 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 time expired before he got anywhere near the front of the line. In fact, he purposely timed his queuing so he would not make it to the front. He then removed the engine cover to reveal that the car had no engine at all. Instead it had a plastic-lined trough filled with ice and five chilled cases of his sponsor's product, which he shared with the other pit crews and race officials. Most in attendance found the gesture to be humorous, however, some officials were not amused. It would be the first of several run-ins Hurtubise would have with USAC officials.
During practice on May 16, Art Pollard wrecked his qualified car. The team was forced to replace it with a back-up car. Pollard, however, suffered a fractured leg, and was out for the month. The team hired Wally Dallenbach (who had been bumped) to drive as a substitute. For race day, the car was moved to the 33rd starting position due to the car/driver change.
The final practice session was scheduled for Wednesday May 24 from 1-4 p.m. Gordon Johncock (186.4 mph) was the fastest car of the day. No accidents were reported, and two drivers (John Mahler and Carl Williams) skipped the session altogether.
The Carburetion Day practice session was expanded to allow the drivers more opportunity to practice under the new Electro-PACER Light system. The new devices were installed around the track to facilitate enforcement of the caution periods. At the time, the pace car was not utilized during caution periods, nor did the field pack up under yellow.
The PACER system featured a series of eight message panels situated around the track at equal intervals. They were programmed to enforce an 80 mph speed limit during caution periods. Drivers were instructed to hold their position under yellow, and each message board around the track would display a number from 1 to 9, illustrating the gap between themselves and the car in front of him. The goal and the requirement was to keep the numbers consistent around the entire circuit. For instance, if a driver saw a "7" on the first board he passed, he was to drive at such a speed that would display a "7" at all of the boards around the circuit. If he saw a "6" on the next board, it illustrated that he was going too fast, and he would have to slow down a bit. If it displayed an "8" on the next board, that meant he was driving too slow, and needed to speed up slightly. Officials were stationed around the track to observe and issue penalties for violating the PACER system, which could be mean a one-lap penalty.
The Electro-PACER Light system would be used at Indianapolis from 1972 through 1978. Despite its seemingly simple format and instructions, it would be the source of ire and controversy during the years it was used. Some drivers found and exploited loopholes in the system, and officials would find it more difficult to police than they expected. The PACER system would be a precursor to later systems such as the Virtual Safety Car and "Slow Zones" introduced in the 2010s in Formula One and at Le Mans, respectively.
One additional rule change for 1972 involved the mandatory pit stops. A minimum of four pit stops (fuel hookup required) was required for 1972. The change was up from two pit stops in 1965–1967, and up from three in 1968–1971. Individual tire changes were still optional, but the rapidly increasing speeds from 1972 on would generate greater tire wear. As a result, tire changes became increasingly necessary and more common. Several drivers won the race in the 1960s without changing any tires, but no longer would that be feasible.
On race morning, track president Tony Hulman was talking with William F. Harrah, owner of Harrah's. Jim Nabors was accompanying Harrah as a guest at the race. Hulman recognized Nabors, and asked him if he wanted to "sing the song" during the pre-race ceremonies. Believing that Hulman was talking about "The Star-Spangled Banner", Nabors agreed, and walked over to arrange with the Purdue Band. Nabors asked the band leader what key they were going to play, and it was not until that moment that he was informed he was going to be singing "Back Home Again in Indiana". A surprised Nabors quickly wrote the lyrics down on a piece of paper, climbed up on a ladder, and performed the song unrehearsed. It was the beginning of a tradition that would see Nabors perform the song at Indianapolis nearly every year through 2014.
Tony Hulman gave the command to start engines, and the field began to pull away for two pace laps. After the pace car crash a year earlier, the veteran driver Jim Rathmann was assigned the pace car driving duties. The passengers in the Hurst/Olds pace car included Tony Hulman, astronaut Pete Conrad, Chris Schenkel of ABC Sports, Bob Draper (Hurst), and Dolly Cole (wife of GM executive Ed Cole), believed to be the first woman ever to ride in the pace car.
As the field pushed off from the starting grid, A. J. Foyt's car stalled and failed to pull away. His crew hurriedly wheeled the car to the south end of the pit, and tried to figure out what was wrong with the machine. With the rest of the field gone, Foyt was possibly out of the race before the green flag. As the field was coming out of turn four, the starter held up one finger, indicating that the pace car should take the field on a second pace lap. However, at that moment the crew got Foyt's car running, and quickly pushed him away. The starter waved the pace car off the track and abruptly dropped the green flag, catching many drivers in the wrong gear to go racing and making for a ragged start. With Foyt slowly coming up to speed on the apron, the field blasted by him into turn one.
Bobby Unser grabbed the lead in the first turn, and led the first 30 laps. Unser set a blistering pace with Mark Donohue and Jerry Grant running close behind. On lap 31, Bobby Unser slowed and headed to the pits with a broken ignition rotor. Unser was out of the race, and Gary Bettenhausen took the lead.
A. J. Foyt was forced to play catch-up from the onset, but was running fast laps in the 180 mph range. His day was short, however, as he blew the turbocharger. After several lengthy pit stops, Foyt dropped out of the race. Among the early outs were Peter Revson (started 2nd) and Johnny Rutherford (started 8th). During a pit stop around lap 42, Jerry Grant and Mark Donohue battled side-by-side as they existed their stalls, and Donohue nearly crashed into the scoring pylon. Meanwhile, a fire broke out in the pit area of Wally Dallenbach, but he was able to continue.
Mike Mosley took the lead on lap 54. Two laps later, he lost a wheel and crashed into the outside wall in turn four. The impact ruptured the fuel tank, and the car caught fire as it slid down the mainstretch. Mosley unbuckled before the car came to a rest and jumped from the car trying to put out the flames. Mosley suffered burns but was not seriously injured. It was the second year in a row Mosley wrecked out in the fourth turn.
On lap 81, for the second time, Wally Dallenbach had a fire in the pits.
At the halfway point, 13 cars were out of the race. Gary Bettenhausen continued to dominate the race, and led at the halfway point. After completing 94 laps, Jim Hurtubise ran out of fuel in turn two. When the safety truck went to tow him back to the pits, they proceeded to tow him through the infield and the garage area gate rather than directly around the track back to his pit stall. He refueled and rejoined the race, but was subsequently disqualified for leaving the race track. Some feel it was a "payback" gesture by USAC for Hurtubise's antics on bump day regarding his 'beer engine.'
Gary Bettenhausen continued to lead, pushing record speeds. Attrition began to take its toll on the field. By the 400-mile mark, eighteen cars were out of the race.
Lee Kunzman lost a wheel in turn two, bringing out a yellow light.
Wally Dallenbach had his third fire in the pits on lap 151. The final round of scheduled pit stops occurred for the leaders around laps 160-165. Bettenhausen pitted first on lap 162, briefly giving the lead over to Jerry Grant. When Grant pitted four laps later, his long pit stop relinquished the lead back to Bettenhausen.
The yellow light came on with about 27 laps to go for debris on the backstretch. When the green light came back on, Gary Bettenhausen's car seemed to hesitate. With 25 laps to go, Bettenhausen suddenly started slowing in the north end of the track. After leading 138 laps, his car quit with ignition trouble. He limped around very slowly for handful of laps, then parked the car in the pits. Jerry Grant blasted by to take the lead, and Mark Donohue was now in second place.
With 13 laps to go, Jerry Grant led Mark Donohue and Al Unser, Sr. Grant was forced to the pits for a bad tire on lap 188. Grant entered the pit area, but he overshot his own pit stall and pulled into the pit box of his teammate Bobby Unser. Grant's crew carried their equipment to Unser's pit and changed Grant's right front tire, and in the confusion Unser's crew refuelled Grant's car with fuel from Unser's pit tank. By the time Grant went back out on the race track he had lost the lead.
With Grant's unscheduled pit stop, Mark Donohue took the lead on lap 188, and Grant dropped to second place on the track. Donohue had about a 1-lap lead over Grant, and third place Al Unser was two laps down. Mike Hiss spun in the southchute between turns 1 and 2 on lap 194, but did not hit the wall. Hiss continued, and the yellow light was on for less than one lap. The green flag came back out with five laps to go.
Donohue led the final 13 laps, and scored his first Indy 500 victory, and the first victory for car owner Roger Penske. Per the rules of the time, the remainder of the field was permitted to continue racing for about five minutes after Donohue took the checkered flag. During that time, Sam Posey and Mario Andretti made pit stops, with Posey taking on fuel and returning to the track to place 5th. Andretti was out of fuel, and dropped from 5th to 8th in the final standings.
In the immediate aftermath of the finish, USAC official Frank Delroy announced there would be no penalty for Grant pitting in the wrong stall. The initial ruling was that no fuel flowed into the tank. However, the decision would be further investigated during the evening, and a final ruling would be made when official results posted at 8:00 a.m. the next morning.
After the race, USAC officials penalized Jerry Grant for taking fuel from Bobby Unser's pit tank. They disqualified him from that point on, and erased the final 12 laps from his tally. He was officially scored as out of the race with 188 laps completed. The penalty elevated Al Unser, Sr. to second place, and dropped Grant to 12th finishing position. According to the rules, each car was allotted a strict limit of only 250 gallons of methanol in their pit-side tank (not including the fuel in the car at the start of the race) to complete the full 500 miles.
The details of the pit snafu were never fully explained, and remains a topic of discussion amongst historians and fans. The team maintained that fueling the car was an unintentional mistake, however, others felt otherwise. It has also been reported by some witnesses that Grant was directed into Unser's pit stall by the crew, while others believe Grant simply overshot his own stall. Several possible theories emerged, with one prevailing opinion suggesting that Grant's car was out of fuel, and his pit-side tank was also empty, due to running high turbocharger boost during the race. Grant supposedly needed fuel to make it to the finish, and since Bobby Unser dropped out early, his pit-side tank was still full. It was thought that Grant deliberately stopped in Unser's pit, aware of the predicament, and knowing Unser's tank would fill his car sufficiently and quicker. Another claim was made to Grant's defense that while the fuel hose was admittedly hooked up, no fuel actually flowed into the car. This claim was quickly dismissed. Grant maintained later in life the infraction was unintentional, maintained his innocence, and felt the penalty was unjust.
Mark Donohue won the race leading only the final 13 laps. The third-lowest total in Indy history to that point (Joe Dawson led two laps in 1912, and Graham Hill led ten laps in 1966). The race was slowed five times for caution for only 20 minutes. Donohue's average speed of 162.962 mph set a new race record that would last until 1984.
Vanguard Racing (of which Leonard W. Miller was involved), became the first African American-owned team to enter a car in the Indy 500. John Mahler (who was white) served as the driver. He dropped out after 99 laps with a broken piston.Note: Jim Hurtubise completed 171 laps which would have unofficially placed him 16th; but he was penalized for being towed through the infield on lap 94, and all subsequent laps were disallowed. Car owner Dick Sommers filed a protest, but it was denied.
First alternate: Wally Dallenbach (#10, #73)
The Pace Car was a 1972 Hurst/Olds convertible with a Hurst Performance modified 455 cubic inch W-30 engine built to pre-smog high compression 1970 specs. It was equipped with a TH-400 transmission and a "His and Hers" Hurst Dual Gate shifter, plus a 3.42 rear axle ratio. An all aluminim W-27 differential cover was used for weight and cooling purposes. Mark Donohue was given the car for winning the race that day. About 629 of these cars were built for public consumption of which 130 were convertibles,220 with sunroofs and the remaining 279 being hardtops. Almost all of these Pace Car replicas had the less powerful L-75 455 engine and 3.23 axle. A W-30 (L-77) could be ordered but only with 1972 specs netting 300HP with only 8.5 compression. All were painted Cameo white and carried unique 3M Firefrost Gold reflective fade out(pin dotted) laser stripes. In addition to this package, special Indy Pace Car decals with festival stickers could be ordered with large H/O stickers adorning the quarter panels.
The race was carried live on the IMS Radio Network. It was carried on over 1,200 affiliates, including shortwave transmission to Japan, Vietnam, the Arctic and Antarctic. The broadcast reached an estimated 100 million listeners worldwide. Sid Collins served as chief announcer and Len Sutton served as "driver expert" for the sixth and final time. At the conclusion of the race, Lou Palmer reported from victory lane.
Sid Collins celebrated his milestone 25th year as chief announcer. During the pre-race coverage, Governor Edgar Whitcomb presented Collins with the Distinguished Hoosier Award, a recognition from American Forces Network, and a personalized letter of recognition from President Richard Nixon. Indianapolis mayor Dick Lugar likewise presented Collins with a silver microphone and declared May 27, 1972, as "Sid Collins Day."
The entire on-air crew remained mostly consistent from 1966–71. Bob Forbes was assigned as "wireless" microphone, covering the garages and roving reports. For 1972, the pre-race coverage expanded from 30 minutes to 45 minutes and came on-air at 10:15 a.m. local time. Howdy Bell's vantage point in turn two (an observation spot against the outside of the retaining wall), would be the final time reporting from that location. Starting in 1973, the vantage point would move to the new VIP Suites.
Jim Shelton (born May 27, 1919), who was reporting his 23rd race on the crew, was also celebrating his 53rd birthday.
The race was carried in the United States on ABC Sports on a same-day tape delay basis. The race was held in the afternoon, and the broadcast aired in prime time later in the day. The two and a half hour broadcast was hosted by Chris Schenkel. Jim McKay and Jackie Stewart served as booth announcers. Chris Economaki was one of the pit reporters.