The 52nd International 500 Mile Sweepstakes was held at the Indianapolis Motor Speedway in Speedway, Indiana on Thursday May 30, 1968. Bobby Unser won the first of his three Indy 500 victories (1968, 1975, 1981). This was the final Indianapolis 500 to feature a front-engined car in the starting field. Of the 33 cars, 32 were rear-engined machines (including three turbines). Jim Hurtubise's entry, which dropped out after only nine laps, was the last front-engine car to race in the 500. This was also the first 500 won by a turbocharged engine.

For the second year in a row, one of Andy Granatelli's STP Turbine-powered machines was leading late in the race, but once again, it failed within sight of victory. On lap 174, Lloyd Ruby's engine misfired allowing Joe Leonard to take the lead in the Lotus 56 Turbine. Leonard, however, suffered a flameout on the lap 191 restart, and rolled to a silent and shocking halt. Unser, in the venerable piston-powered Offenhauser, inherited the lead and won the race despite gear linkage trouble.

During the month, film crews were on hand to film various action shots and stock footage of the race proceedings to be used in the 1969 film Winning, starring Paul Newman.

With of precipitation in the Indianapolis area in May, the 1968 race featured the wettest month on record for the Indy 500. Rain hampered practice and qualifying, but did not affect race day. This was the most recent Indy 500 scheduled for Thursday; the Uniform Monday Holiday Act was implemented in 1971 and Memorial Day became a three-day weekend (Saturday–Monday) every year. A day previously avoided, Sunday became the scheduled race day beginning in 1974.

Race schedule Time trials was scheduled for four days, but for the first time under the current schedule format, qualifying was carried over into a fifth day. Most of Bump Day (May 26) was rained out, and the track closed due to darkness with the field not yet filled to 33 cars. A special session was held Monday in order to complete the field.

Race schedule — May 1968SunMonTueWedThuFriSat    1Practice 2Practice 3Practice 4Practice 5Practice 6Practice 7Practice 8Practice 9Practice10Practice11Practice12Practice13Practice14Practice15Practice16Practice17Practice18Pole Day19Time Trials20Practice21Practice22Practice23Practice24Practice25Time Trials26Bump Day27Time Trials28Carb DayParade29Meeting30Indy 50031Banquet  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 The 500 Festival Parade was held Tuesday night, May 28.

Practice and time trials

The 1968 Indianapolis 500 was the second and ultimately the final year of participation by the controversial STP Granatelli Turbine machines. For 1968, the Pratt & Whitney turbine engine was installed in the Lotus 56 chassis, often known colloquially as the "Wedge Turbine," and sometimes affectionately as the "Doorstop." In a veiled effort to curtail the turbine's power output, USAC had imposed revised regulations regarding the maximum annulus inlet (reduced from 23.999 in2 to 15.999 in2).

Another rule change dictated that cars were required to conduct three mandatory pit stops, up from two that were required from 1965 to 1967.

Mike Spence was fatally injured after a crash in turn one on May 7. A tire broke off his Lotus "Wedge" Turbine and struck him in the head. He died of his injuries a few hours after the accident after being taken to the hospital. Spence's death came one month after Jim Clark's fatal accident at Hockenheim. Clark was scheduled to drive one of the Lotus Wedge Turbines at Indy, and had tested one of the machines just prior to his death.

Pole Day Time trials – Saturday May 18 Graham Hill, the 1966 winner, in the #70 STP Turbine, was first to qualify and set a new qualifying record. Later, his STP Lotus 56 teammate Joe Leonard in #60 won the pole position with a four-lap average speed of . Despite the expected dominance of the Turbines, Bobby Unser put his turbocharged Offenhauser on the outside of the front row at a noteworthy 169.507 mph.

Second Day time trials – Sunday May 19 Rain kept cars off the track most of the day. Only two cars were able to make an attempt, and only one was run to completion. At 5:45 p.m., the track was finally opened for qualifications, and Jochen Rindt was the lone qualifier at , while Denny Hulme waved off as the 6 o'clock gun went off.

At the conclusion of the first weekend of time trials, the field was filled to 16 cars.

Third Day time trials – Saturday May 25 Sixteen cars made a total of 24 attempts, and filled the field to 26 cars. High winds kept some cars off the track, and speeds were down from the previous weekend. Many cars waved off, and Mel Kenyon, at , was the fastest of the day.

After qualifying, Ronnie Bucknum's car was disqualified for being underweight.

Fourth day time trials – Sunday May 26 With the field filled to 25 cars (eight spots open), rain kept the cars off the track until late in the day. The final scheduled day of time trials ("Bump Day") was almost a complete wash out. The traditional 6 o'clock closing time came and went, and the track was still wet. Track crews continued to work, and the track opened for practice at 6:55 p.m. After the mandatory 30-minute practice session, the track opened for time trials at 7:31 p.m.

With overcast skies and darkness looming, three cars made attempts. Bill Puterbaugh and Bill Cheesbourg completed runs, while Bobby Johns spun on his second warm up lap. At that time, officials deemed the conditions unsafe due to darkness, and postponed the remainder of qualifying until Monday morning.

Time trials – Monday May 27 For the first time since 1952, time trials were pushed into a fifth day. Officials ruled that all 25 cars that were in the starting field at 6 p.m. Sunday (May 26) were "locked in" and could not be bumped. In addition, all cars that were in line to qualify Sunday evening at 7:54 p.m. were eligible to make one qualifying attempt on Monday. Only cars that qualified after 6 p.m. on Sunday evening were subject to bumping (including Puterbaugh and Cheesbourg).

Ronnie Bucknum was reinstated to the field when it was determined that during his inspection, the scale used to weight the car was defective. With Bucknum's car back in the field, only seven spots were now available.

Though rain hampered the day, the qualifying was successfully completed on Monday. A frantic session saw two crashes (Bob Hurt and Rick Muther). Eighteen cars took to the track to fill the seven open spots. Both Puterbaugh and Cheesebourg were bumped, and Mike Mosley was the fastest of the day. Jim Hurtubise qualified his front-engined Mallard for 30th starting position. It would be the final front-engined car to qualify for the Indy 500.

Qualification Chronology Att#Car#DriverLapsQualSpeedRankStartCommentSaturday May 18, 1968 1 70 Graham Hill 4 171.208 2 2 2 25 Lloyd Ruby 4 167.613 5 5 3 8 Roger McCluskey 4 166.976 7 7 4 15 Mel Kenyon 2 — — — Waved off 5 54 Wally Dallenbach 3 — — — Waved off 6 3 Bobby Unser 4 169.507 3 3 7 4 Gordon Johncock 3 — — — Waved off 8 1 A. J. Foyt 4 166.821 8 8 9 48 Dan Gurney 4 166.512 10 10 10 27 Jim Malloy 4 165.032 15 14 11 60 Joe Leonard 4 171.559 1 1 12 4 Gordon Johncock 4 166.775 9 9 13 82 Jim McElreath 4 165.512 13 13 14 24 Al Unser 4 167.069 6 6 15 2 Mario Andretti 4 167.691 4 4 16 54 Wally Dallenbach 4 165.548 12 12 17 56 Jim Hurtubise 1 — — — Accident 18 78 Jerry Grant 4 164.782 16 15 19 20 Art Pollard 4 166.297 11 11Sunday May 19, 1968 20 35 Jochen Rindt 4 164.144 20 16 21 42 Denis Hulme 3 — — — Waved offSaturday May 25, 1968 22 21 Arnie Knepper 1 — — — Accident 23 15 Mel Kenyon 3 — — — Waved off 24 62 Bruce Walkup 3 — — — 25 11 Gary Bettenhausen 4 163.562 22 22 26 18 Johnny Rutherford 4 163.830 21 21 27 45 Ronnie Bucknum 4 164.211 18 19 Disqualified 5/25; Reinstated 5/27; Bumps #88 28 88 Bob Harkey 3 — — — Waved off 29 36 Larry Dickson 3 — — — Waved off 30 59 Ronnie Duman 4 162.338 27 26 31 98 Billy Vukovich II 4 163.510 23 23 32 26 Bobby Johns 3 — — — Waved off 33 14 Bob Hurt 3 — — — Waved off 34 16 Bob Veith 4 163.495 24 24 35 10 Bud Tingelstad 1 — — — Pulled off 36 90 Mike Mosley 2 — — — Waved off 37 6 Bobby Grim 4 162.866 25 25 38 84 Carl Williams 2 — — — Waved off 39 26 Bobby Johns 3 — — — Waved off 40 10 Bud Tingelstad 4 164.444 17 18 41 21 Arnie Knepper 3 — — — Waved off 42 42 Denis Hulme 4 164.189 19 20 43 15 Mel Kenyon 4 165.191 14 17 44 84 Carl Williams 3 — — — Waved off 45 36 Larry Dickson 3 — — — Waved offSunday May 26, 1968 46 77 Bill Puterbaugh 4 157.301 — — Bumped by #84 47 22 Bill Cheesbourg 4 157.274 — — Bumped by #21 Bobby Johns 157.274 — — Spun on second warm up lap Monday May 27, 1968 48 88 Bob Harkey 4 159.915 — — Bumped by #45 reinstatement 49 90 Mike Mosley 4 162.449 26 27 50 41 George Follmer 4 158.877 — — Bumped by #62 51 28 Rick Muther 2 — — — Accident 52 94 Sam Sessions 4 162.118 31 31 53 31 Sonny Ates 4 158.221 — — Bumped by #29 54 36 Larry Dickson 4 159.652 — — Bumped by #56 55 21 Arnie Knepper 4 161.900 32 32 Bumps #22 56 84 Carl Williams 4 162.232 29 29 Bumps #77 57 29 George Snider 4 162.264 28 28 Bumps #31 58 62 Bruce Walkup 4 160.514 — — Bumps #41; Bumped by #64 59 56 Jim Hurtubise 4 162.191 30 30 Bumps #36 60 32 Al Miller II 4 157.109 — — Too slow 61 71 Bob Harkey 4 156.257 — — Too slow 62 64 Larry Dickson 4 161.124 33 33 Bumps #88 63 76 Jerry Titus 4 154.540 — — Too slow

Starting grid RowInsideMiddleOutside 160 Joe Leonard70 Graham Hill 3 Bobby Unser 22 Mario Andretti25 Lloyd Ruby24 Al Unser 38 Roger McCluskey1 A. J. Foyt 4 Gordon Johncock 448 Dan Gurney20 Art Pollard54 Wally Dallenbach Sr. 582 Jim McElreath27 Jim Malloy 78 Jerry Grant 635 Jochen Rindt15 Mel Kenyon10 Bud Tingelstad 745 Ronnie Bucknum 42 Denny Hulme18 Johnny Rutherford 811 Gary Bettenhausen 98 Bill Vukovich II 16 Bob Veith 96 Bobby Grim59 Ronnie Duman90 Mike Mosley 1084 Carl Williams29 George Snider56 Jim Hurtubise 1194 Sammy Sessions 21 Arnie Knepper64 Larry Dickson

Alternates First alternate: Bruce Walkup (#59, #62)The Talk of Gasoline Alley - 1070-AM WIBC, May 14, 2004

Failed to qualify Otto Becker (#46) - Entry Declined Sonny Ates (#19, #31) Rollie Beale (#32, #88) Chuck Booth (#34) – Entered, did not drive Bill Cheesbourg (#22, #75, #81) Jim Clark – Withdrawn after his death on April 7 George Follmer (#28, #41, #42) Masten Gregory (#28, #95) Bob Harkey (#71, #77, #88) Chuck Hulse (#90) – Wrecked practice, retired Bob Hurt (#11, #14, #36, #72, #81, #90) Bobby Johns (#17, #25) Dee Jones (#34, #46) Ralph Ligouri (#71, #77, #88) Bruce McLaren (#66, #69) Al Miller (#9, #32) Rick Muther (#22, #28) Danny Ongais (#63) – Entry declined, lack of experience Henry Pens (#17) – Entry declined, lack of experience Bill Puterbaugh (#63, #71, #77) Les Scott (#50) – Failed refresher test Mike Spence (#30, #60) – Fatal accident Chuck Stevenson (#90) – Wrecked, retired Jackie Stewart (#20) Jerry Titus (#50, #71, #75, #76) Greg Weld (#17, #19, #30) Dempsey Wilson (#51, #63, #81) LeeRoy Yarbrough (#59, #62)

Race Day

First half At the drop of the green flag, Joe Leonard in the #60 STP Turbine took the lead, with Bobby Unser in second and Roger McCluskey up to third at the end of lap one. A fast pace was set over the first 100 miles, with no yellow caution lights. Bobby Unser took the lead for the first time on lap 8, and led most of the first half.

After only nine laps, Jim Hurtubise in the front-engined PepsiCo Frito-lay special had burned a piston, and was out, finishing 30th, the final front-engined "roadster" to race at lap at the 500. Also in the pits was Mario Andretti, who dropped out with a bad piston. Moments later, he hopped into the car of his teammate Larry Dickson, but that was also short-lived. That car also suffered a broken piston after 24 laps.