The replacement of hydraulic and mechanical systems in motor vehicles with electronic controls. For example, instead of a physical linkage from the accelerator to the engine or from the steering wheel to the wheels, sensors detect the driver's movements and send signals to actuators that move the throttle and turn the wheels. Instead of a cable that rotates a speedometer dial, signals are sent to an electronic readout. Drive-by-wire also refers to sensor-based systems that automatically try to avoid a collision when another vehicle comes too close. Various aspects of drive-by-wire are making cars safer. See automotive systems, embedded systems and CAN bus.