text: The new driver-less cars have sensors. Google's modified Toyota Prius uses position-estimating sensors on the left rear wheel, a rotating sensor on the roof, a video camera mounted near the rearview mirror, four automotive radar sensors, a GPS reciever, and an inertial motion sensor. Automakers use speed sensors at the wheels in the creation of antilock brakes. The information from the sensors can cause the car to apply brakes on individual wheels and reduce power from the engine, allowing far better response and control than a human driver could manage alone.