Nissan really wants to do something about drinking and driving, so it has come up with a system that integrates alcohol odor sensors in the front seats and gearshift, a facial recognition system that determines the driver's state of consciousness via eye blinking, and a driving behavior system that senses if the car is staying in its lane or not.
If the gearshift sensor (pictured) detects alcohol in the driver's perspiration, it automatically locks the gearshift and prevents the car from being driven. There are also visual and audio warnings on the navigation screen, and the seatbelts can be automatically tightened to get the driver's attention.
This might not be a bad idea; I'm sure many drunk driving accidents are caused when people think they're a little buzzed, but not drunk (but of course have no clue what their blood-alcohol level is, and how it impacts their reaction time and decision making abilities).
It's easy for me to see how this system could be a useful safety device. For example, I was at a wedding in June and was the designated driver. I was expecting to take seven people to the hotel from the reception, and many of my friends were really inebriated at one time or another during the night. Eventually, all but one drove themselves to the hotel (after several hours of not drinking, and assuring me that they were "fine,") and the one who rode with me only did so because I shamed him into it, as he was the one who had me unfolding seats, taking out the child seat, and going to the trouble of getting our SUV into maximum passenger carrying mode.
Once we were back at the hotel (thank God everyone made it there OK), one of the friends who was supposed to ride with me later said that he realized about halfway into his trip that he shouldn't have been driving. Lucky for him and everyone else on the road at the same time, he didn't have any problems, but obviously he could have at some point. He just didn't know objectively what his blood alcohol level was, but this system would have kept him in the passenger seat where he belonged.