I seriously doubt the driverless car will ever be able to evade the sudden danger posed by a jacknifed 18-wheeler or a car that jumps the median from the opposite direction. There's almost no chance a car with a driver could either, but instinct running on adrenaline-fueled impulse could actually give the human driver a fighting chance, especially if the driver is observant to the point of noticing something wrong about a driver in the next lane. (I am assuming there will be a mix of both types of cars/trucks sharing the road for quite some time.) Your driverless car is not likely to take note of another driver's distracted behavior, for example.