In 1967 the turbine engine powered car driven by Parnelli Jones dominated the race, only to drop out while leading with four laps to go. A. J. Foyt went on to win his third Indianapolis 500 in six years. For 1968 the turbine engine cars were back in force,determined to flip the sport to a new breed of power. STP entered three cars, and five other turbine cars also came to try to make the race. It appeared a different kind of power was about to erase 70 years of internal combustion technology.

The front row featured two turbines in the first two spots and Bobby Unser in the third spot. Unser, entering his sixth race, began the 1968 race with a best finish of eighth in 1966, a race which saw only seven cars running at the end. Joe Leonard on the pole and 1966 winner Graham Hill next to him on the grid were expected to run away with the event.

While the power of the cars appeared poised for a transition, the 1968 race program reflected other transitions. The memorial page acknowledged the death of Ray Harroun, winner of the first 500 in 1911, on January 19. A more recent winner, Jim Clark , who ran away with the 1965 race, lost his life in a Formula 2 accident in Hockenheim, Germany, April 7. The deaths were almost bookends of the race’s history to that point.

STP bought a full page ad touting the turbine, calling it “A Quiet revolution.

A new product which would revolutionize consumer spending was in its infancy in 1968- the credit card. Most were specific to a product, and some were beginning to expand their use, like the Standard Oil card. Notice the 10 digit number.

1968 featured one of the hot air balloon races, honoring the first event held at IMS in 1909. The third day day of qualifying paused for two hours as the balloons launched. There was generally a lot of down time on Day 3 of qualifying, but in 1968 the constant rain put track time at a premium. The balloon races ended a couple years later when the basket of a competitor couldn’t launch in the wind and plowed into an infield restroom.

Back to the race:

Unser passed Leonard for the lead on lap 8. the race turned into a three way battle between Unser, Leonard, and Lloyd Ruby. Leonard took the lead on lap 175 and appeared headed for victory. As the race restarted on lap 191, Leonard’s car suddenly came to a halt in turn 1 with a fuekl shaft problem. Unser went on to claim the first of his three 500 mile race wins. it was also the first of nine wins for the Unser family.

In June USAC limited the air inlet of turbines to 12.5 square inches from the 15.9 they had been allowed. The smaller intake rendered them uncompetitive. Only one turbine entered the race the next year, and then the silent revolution disappeared.