Starting in 1971, the traditional 100-mile races held on the one mile state fairgrounds dirt tracks no longer counted towards the USAC National Championship Series. Instead, those races became their own series. In 1970, the final year under the old system, five dirt races were included in the championship, and title-bound Al Unser won all five with this Ford V8 powered Grant King-built car, known as the Johnny Lightning Special.
Having already won two races with the car, in its 1969 debut, Al also captured three of the five starts in the new series in 1971 and 1972. For 1973 and 1974, the team added a second car for Mario Andretti. They combined to win seven out of eight races. Al won the series championship in 1973, with Mario taking home the championship in 1974. Between 1970 and 1973, Al went 'four for four' in the famed Hoosier Hundred at the Indiana State Fairgrounds.
The history of this car is as follows:
- 1969 Winner in 2 of 4 USAC Championship Dirt Car races entered.
- 1970 Winner of all 5 USAC Championship Dirt Races and was USAC National Dirt Car Championship.
- 1971 Winner of 1 of 2 events entered. Finished 2nd in USAC Dirt Car Points.
- 1972 Winner in 2 of 2 events entered. Finished 2nd in USAC Dirt Car points.
- 1973 Winner in 1 of 3 events entered. Finished in top 5 in all 3 events and won USAC Dirt Car Championship
- 1974 Winner in 1 of 4 events entered. Finished in the top 3, three times. Finished 3rd in USAC National Dirt Car points.
- 1975 Winner in 1 of 4 events entered. Finished 2nd in USAC National Dirt Car points.