Today's leading casting manufacturers employ many new technologies to produce high quality engineered castings. Foremost among these technologies is casting process simulation. With casting process simulation, casting designers and process engineers use sophisticated physical models to optimize casting filling and solidification patterns, microstructure and mechanical properties distributions, and residual stresses and distortion. Using casting process simulation early in the development cycle leads not only to higher quality castings, but also to shorter product development times, more castable designs, higher productivity, and castings that go well beyond what were once considered to be the limits of the casting process. This paper illustrates through case studies how both designers and producers of castings are using simulation to meet the increasing demands being placed on castings by the automotive and transportation industries.