I have a car with "adaptive cruise control", which is a far cry from full autonomy but gives a flavor. It doesn't feel like it defaults toward yield. It defaults toward assuming that the car in front will keep moving, but responds quickly when the speed changes, and responds more forcefully when there is sudden deceleration ahead. I haven't experienced a full panic stop, and I don't want to - I continue to "drive", with my foot near the pedals if earlier intervention is called for. Once or twice, it has stepped in to override my choice to let the distance decrease when a driver pulls into my lane, say from a parking lot, and as a human I know the other guy will accelerate smartly but the camera/computer isn't so sure - I was ready to brake but didn't expect to need to, but suddenly my car was decelerating anyway, and I said to myself that maybe I was being a little too aggressive. I am nowhere near ready to trust my life (or anyone else's outside) with the technology in my vehicle, but then again mine is 2015 technology and it already gives me a pretty warm feeling about where we're headed. We need several more years of fine tuning based on real-life feedback on limited access roads, but we're getting there.