Micromachined silicon sensors offer tremendous cost, size, and reliability improvements for guidance, navigation, and control (GN&C). Currently the development of micro-electromechanical systems (MEMS) inertial sensors is largely supported by DoD; however, it will ultimately be driven by high-volume commercial markets with target prices below $25 per instrument. The paper describes advances in micromechanical gyro and accelerometer design and packaging. Performance of a prototype automotive traction control module, in pilot production, and a planned automobile suspension control module are described. The concept of a 3-cubic-inch, multi-purpose MEMS inertial system, based on a three-gyro, three-accelerometer system under development for a guided artillery shell, is discussed for automotive applications. Plans for future cost and size reduction are presented.