1978 Indianapolis 500

The 62nd 500 Mile International Sweepstakes was held at the Indianapolis Motor Speedway in Speedway, Indiana on Sunday, May 28, 1978. Danny Ongais dominated the early stages of the race but eventually dropped out with a blown engine. Al Unser Sr. dominated the second half, and held a large lead late in the race. However, Unser bent the front wing of his Lola during a pit stop on lap 180, causing his handling to go away over the final twenty laps. Second place Tom Sneva charged to catch Unser's crippled Lola but came up 8 seconds short at the finish line – the second-closest finish in Indy history to that point. Unser held off the challenge, and became a three-time winner of the 500. It was Al Unser's third Indy victory in the decade of the 1970s, and the fifth of nine overall victories by the Unser family.

Al Unser Sr. entered the month having won the 1977 California 500 at Ontario the previous September. Later in the 1978 season, Unser would go on to win the Pocono 500 and the California 500 again, sweeping the "triple crown" of Indy car racing for 1978. As of 2015 (the last year there was a "Triple Crown") Unser is the only driver in history to win all three 500-mile "triple crown" races in the same season, and coupled with the win at Ontario in 1977, set a record by winning four straight 500-mile Indy car races.

Second year driver Janet Guthrie finished ninth, and it was later revealed she drove with a fractured wrist. It was the highest finish for a female driver in Indy history until Danica Patrick finished in fourth place in 2005. During time trials, Tom Sneva, who had broken the 200 mph (320 km/h) barrier a year earlier, bettered his own record. This time he managed to complete all four qualifying laps over 200 mph (320 km/h), setting once again new one-lap and four-lap track records.

Tony Hulman, the popular owner and president of the track since 1945, died the previous October. His widow Mary F. Hulman was named the chairperson of the board of the Speedway, and for the first time she delivered the famous starting command. Along with the death of Tony Hulman, the race was held just five weeks after eight USAC officials were killed in a plane crash. With dissent increasing among the participants about organizational issues and poor revenue, the 1978 race would be the final Indy 500 contested prior to the formation of CART and prior to the first open wheel "split."

Al Unser's victory was the first Indy triumph for the Cosworth DFX V8 engine. The British-based engine building company would go on to win the Indianapolis 500 for ten consecutive years.

For 1978, the turbocharger "boost" settings were set at 80 inHg, the same regulations used in 1974–1975 and 1977. The first weekend of time trials was scheduled for May 13–14. Rain, however, washed out the entire first weekend. Pole qualifying was moved to Saturday May 20.

On Wednesday May 10, Mario Andretti turned a practice lap of 201.838 mph (324.827 km/h), faster than the track record. Minutes later, Danny Ongais upped the best speed to 201.974 mph (325.046 km/h). On Thursday May 11, rookie Rick Mears also joined the coveted "200 mph club" in practice. Johnny Rutherford (199.2 mph (320.6 km/h)) and A. J. Foyt (199.158 mph (320.514 km/h)) were also within striking distance.

On Friday May 12, the final day of practice before pole qualifying was scheduled to be held, Mario Andretti shattered the unofficial track record, turning a lap of 203.482 mph (327.473 km/h). Also over 200 mph (320 km/h) were Mears, Rutherford, and Foyt. Tom Sneva, the driver who broke the 200 mph barrier a year earlier, was the slowest of the three Penske cars, managing only a 196.3 mph (315.9 km/h) lap during practice.