I'm barreling along at about 60 mph in a Cadillac SRX, and I'm Tweeting to the world while doing it — using both hands. The cruise control is set, and both of my passengers appear calm and relaxed while I do it. I'm keeping an eye on our situation, but I'm not doing any actual driving — I'm as much a passenger in this car as the guy sitting shotgun. That's because this particular Caddy is currently driving itself, automatically following the curving road in front of me and responding to changes in the speed of the car in front of me.
This is what Cadillac calls "Super Cruise" mode — the next step on the path to fully autonomous vehicles, and it's coming to a Cadillac near you before the decade is out.