Between 1967 and 1971, Pratt &amp; Whitney turbine engines were used in American Championship Car Racing and Formula One. The STP-Paxton Turbocar dominated the 1967 Indianapolis 500 until a transmission bearing failed four laps from the finish. STP entered four Lotus 56s in the 1968 Indianapolis 500. One car crashed during qualifying. Two of the remaining cars qualified fastest and second fastest, but all three retired from the race. Turbine cars were deemed illegal before the following year's race, so Lotus chief Colin Chapman developed the car for use in Formula One and an updated 56B competed in half a dozen Formula One races in 1971.