I think this was the main thing that hasn't been shown with data before: "One of those analyses showed that when a human was behind the wheel, Google’s cars acc

I think this was the main thing that hasn't been shown with data before: "One of those analyses showed that when a human was behind the wheel, Google’s cars accelerated and braked significantly more sharply than they did when piloting themselves. Another showed that the cars’ software was much better at maintaining a safe distance from the vehicle ahead than the human drivers were." They were known to be very safe with a very low (almost non-existant) accident rate, but I believe this was the first presentation of some of the more detailed driving data such as acceleration and braking.