text: These new and improved cars have positive things about them. Their cars have driven more than half a million miles without a car. Half a million miles is quite a lot without anything going wrong. it goes to show they can be reliable when wanting to drive a greater distance. There is more about these self-driving cars many dont know. Gm had developed driver's seats that vibrate when the vehicle is in a danger of backing into an object. Therefor, the Google car simply announces when the driver should be prepared to take over.