If ALL cars were automated there should be no car to car accidents as they will all communicate with each other and at the first sign of trouble by one car all the others in the vicinity will know to slow down.
But, in a hybrid world where the auto cars have to deal with humans we will have a lot of problems.
1. The auto car will be programmed to be nervous nellies. Since they cannot predict what the crazy humans do, they will stomp on the brakes at any sign of trouble.
1.1 I expect Humans to be very confused by the behaviour of the auto cars and cause accidents. Who gets blamed then?
2. I expect Humans to maliciously mess with the auto cars, brake check them, etc.
3. Unless a unified auto car communication and behaviour protocol is created I expect many of the auto cars from different manufacturers to exhibit behaviours that will look bizarre to a human. 4-way stop sign resolution for example.