I think what will happen is there will end up being 2 modes of travel. First would be attended mode where there is a driver available and ready to jump in in case of trouble. This mode would be allowed for highway travel, high risk travel, etc where something could go catastrophically wrong. The second mode would…

Can a passenger drink in the car while the driver doesn't?

If you car was driving itself perfectly there would be no reason for an officer to suspect drinking and driving no matter how wasted the person behind the wheel was.

Why else would I buy one?