The NVIDIA Drive PX 2 computer used in new Tesla cars for eventual full self driving consumes 250W of power. To that add 8 cameras, RADAR and ultrasonic sensors—also add the liquid cooling system required by the computer. read more
A computer for Autopilot would have to power the sensors and the computer itself. It would surprise me very much if as a system it took a lot more than 100, maybe 200 W with lidar and other active sensors that have to send out beams. read more