Google will drive 2 million miles, and Google will drive 2 million more

Getting self-driving cars to the point where they're safe enough for the public isn't a matter of time -- it's a matter of distance. The more miles driven, the more prepared autonomous cars should be for real-world use, and Google's just reached a milestone on this journey.

Google's fleet of autonomous vehicles just reached a self-driven distance of 2 million miles, according to a blog post from Dmitri Dolgov, Google's head of self-driving tech. The first million miles took six years to achieve, while the second took just 16 months. "Our cars now have the equivalent of 300 years of human driving experience," Dolgov wrote.

To start, the research focused on the "easy" parts of driving -- long slogs on relatively uncomplicated highways. As time went on, the development made its way onto urban roads, a more complex environment with more rules, and more exceptions to those rules. That's where the majority of its testing takes place now.

Driving is an inherently social exercise, and relaying that into a self-driving car's algorithms was absolutely necessary. Teaching its cars how to react to and live alongside cyclists, emergency vehicles and pedestrians is not easy, but it's happening, and it's making Google's cars better.

Google's cars still have drivers, but they serve as more than emergency backups in the event the computer cannot handle a given situation. These drivers provide feedback on the feel of Google's fleet -- acceleration, braking, lane changes and the like -- in an attempt to make the car's movements feel as "human" as possible.

While there's no special honor or reward that comes with 2 million autonomously driven miles, it's still important to both Google and the world at large. The more miles these cars drive, the better they will be when something out of the ordinary pops up. Here's to 2 million more.