The information needs of engines have increased dramatically over recent years. In order to achieve the levels of performance and endurance that are now required in the marketplace, engine operation increasingly employs sophisticated control with closed-loop operation of various functions. This control trend will continue as performance expectations increase, calibration times reduce and systems become more complex and dependent on a variety of sensors.Available and emerging technologies offer a range of solutions for sensor systems but success in any particular application is often difficult to analyze. This makes the prediction of future trends more difficult. This paper looks back at some recent developments and forward to the next few years. In addition to the sensors required, some consideration is also given to control systems, which have increased dramatically in sophistication.Some developments are likely to become increasingly important, for both performance and legislative reasons. These include high-speed control, where individual combustion events are recognized, and optical connections between sensors, to achieve high bandwidths.The use of low-cost computing elements is a distinguishing feature for many sensors today, and the impact of this rapidly developing technology on emerging and future sensors is recognized.Sensor technology is also moving towards more closely integrated products, in both mechanical and electronic terms. The development of communication systems in-vehicle, as well as between vehicles, will lead to ‘distributed’ sensors for complex information.