IIRC, the autonomous cars all use a LIDAR system (kind of radar) to detect objects, and do not fully rely on computer vision.

Also, here's ([1]) an article about a student who (single-handedly!) wrote the software for a self-driving car, which doesn't use a LIDAR system and is much cheaper.

[1] http://www.nbcnews.com/technology/students-self-driving-car-...