[danweber]

From what I know it's always known-course. If you were to get a google car today for your commute (you can't), you would first drive to and from work yourself, probably more than once, so it can map everything.

Knowing where there should be a stop sign and traffic lights significantly reduces risks. The computer still needs to be able to learn when new ones appear, of course.

[protomyth]

It would also help with some roads that are incorrectly marked on the GPS. There is a highway in ND that has a 4 mile stretch that has a miss marked road. Multiple GPS maps show the road about 100 yards west of where it actually is. Damn annoying driving 4 miles with the GPS constantly saying "Get back on the road". Thought it was just a garbage GPS map, but it happened on a couple of models.

Guess I really don't have to worry until they figure out how to get the car to drive on snow covered roads.