I would guess that it's still your responsibility as you're supervising the car while it's been driven by Google's software. The same way you're responsible for your speed even if you're using cruise control.

That's the current problem. If it gets into litigation, whose fault is it?

Currently, the person who is operating the vehicle is responsible for what the car does.

If it is gcar on gcar, it is googles fault, because they programmed it wrong / poorly.

If it is gcar on car, with the normal car responsible, it is the traditional fault model.

If it is car on gcar and it is gcars fault, Google really fudged it up.

If it is no ones fault (ie, falling rocks on top of the thing) then that falls into the same catagory as natural disaster damage.

I would hope, at least.