Austempered Ductile Iron was first commercially applied in 1972. By the mid 1970's it had found its way into Chinese Military trucks and into commercial truck applications in Europe. By 1978, austempered ductile iron had been applied to light cars and trucks in the US. Today, it is estimated that over 50,000 tons per year of austempered ductile iron components are installed in cars and trucks world-wide. That production appears to be growing at a rate of exceeding 10% per year. As a family of materials, austempered ductile iron capably addresses the issues of weight, strength, stiffness, noise, cost and recyclability. From the first differential gear sets installed by General Motors in 1978, to light-weight truck-trailer wheel hubs, to high performance automobile suspensions, austempered ductile iron has found itself in many unique applications. This paper will review those applications, the reason(s) for the conversions, and the performance of those components.