![Riding in prototype of fully autonomous Nissan Leaf electric car, March 2017 [video: Fully Charged]](http://images.hgmsites.net/tmb/riding-in-prototype-of-fully-autonomous-nissan-leaf-electric-car-march-2017-video-fully-charged_100598167_t.gif)
It's been a vision of the future for decades now: self-driving cars that let you get in, specify your destination, and then curl up for a bit more sleep, waking when you arrive. That kind of anywhere-any-time autonomy remains some years in the future, most engineers suggest. Automakers are already adding individual active-safety systems that will...