text: Finally, this could be expensive. Google has a modified Toyota Prius that contains position-estimating sensors on the left rear wheel, a rotating sensor on the roof, a video camers mounted near the rearview mirror, four automotive radar sensors, a GPS receiver, and an intertial motion sensor. This technology all works together to produce a 3-D model of the cars surroundings. If this car is not even driverless, how much technology would be needed for a driverless car? It could get very pricey.