Although Google has started showing off its driverless car to the media, there are still a surprising number of questions left unasked about how it operates. Some of these questions are hiding in plain sight.
When you step into the prototype vehicle, you're confronted with just four buttons -- start, stop, windows up/down, and temperature control. Google has taken the steering wheel out altogether. The car takes care of everything you'd normally do.
But what about the horn?
Will the car stay stoically silent when it gets cut off? Will it ignore the idiots at every intersection? Or will it be more like the car from this year's NPR April Fools' parody, with a perfectly-programmed modicum of road rage?
"Yes, the car does honk," a Google spokesperson told Mashable. "It honks when another vehicle is moving toward it and does not appear to be aware of its presence."
In one real-world example, the spokesperson added, "when another car is backing out of a driveway just as the self-driving car is passing by, a brief honk lets them know that the car is there."
What we still don't know is whether the car will honk in reverse, as it were -- alerting cars that are about to rear-end it. This is a surprisingly common occurrence for the Google car; in their combined 1.2 million miles on the road, the prototype vehicles have been hit from behind roughly a dozen times, nearly all when stopped at lights. (The cars have never themselves hit anyone while in autonomous mode.)
Here's one example of a Google car being rear-ended, from the perspective of the car's computer:
Most of these impacts were too light to even file an accident report; still, Google is erring on the side of full disclosure. A rear-end horn would make sense if the car wants a completely unblemished safety record, but it might still be a novel concept for other drivers. Humans are usually blindsided by a rear-ending situation. A car with an unblinking 360-degree field of vision, however, backed up by lasers and radar, would be able to see it coming.