Electronic fuel management has clearly shown that improved vehicle performance can be achieved by replacing mechanical control systems with those that are electronic. Based on the recent success of fuel management applications and other significant projects underway, all major automotive systems will contain electronic controls in the near future. It is increasingly obvious that sensors and actuators are the limiting factors in the introduction of these systems. However, micromachining technology has emerged from research; it promises for sensors and actuators the same accelerated performance and cost-improvements that microprocessors experienced in recent years. This paper describes silicon micromachining and the structures it can fabricate, reviews the present status of this technology, and discusses its potential for low-cost smart sensors.