At this point, you're probably aware of at least a few basic things about autonomous cars: They're expected to eventually become the standard in personal vehicle transportation, Alphabet's (GOOG 1.48%) (GOOGL 1.54%) Google has a platoon of them it's testing on a constant basis, and certain technologies they will feature are already available in today's more advanced vehicle models.

But there's more to know about this most high-profile of vehicle innovations. With that in mind, here are a few interesting facts to chew on while we wait for autopiloted cars to whisk us down the road.

IMAGE SOURCE: VOLVO. 

1. An entire city has been built for them
One of the major concerns about self-driving cars is how they'll handle the many obstacles human drivers face on a regular basis -- especially in populated areas. To simulate such an environment, researchers at the University of Michigan (in conjunction with the state's Department of Transportation) have designed and built a small municipality called Mcity.

It's one big testing facility for autonomous cars, or more precisely, in the University's words, it "simulates the broad range of complexities vehicles encounter in urban and suburban environments."

These include, but are by no means limited to, roads with rough surfaces and no lane markings, four-way intersections, and construction barriers. There's even a fake underpass to test crucial technologies such as vehicle-to-vehicle communications.

2. Forget cross-country trips: A convoy of autonomous vehicles once traveled over continents
There's a chance you've heard about the Audi AQ5 SUV that last year drove itself from San Francisco to New York City, with the enormous help of technology provided by Delphi (DLPH).

That nearly 3,400-mile journey, however, pales compared to that undertaken by a quartet of cars using technology developed by researchers at Italy's University of Parma. That caravan motored from its home city, across Europe and into Asia, finally stopping in Shanghai. All told, it covered roughly nearly 10,000 miles in 100 days, traveling through nine countries.

More impressively, this journey was made when autonomous driving was still not a constant topic of discussion among car cognoscenti -- it took place in 2010.

3. They have competed for big prize money from the military
The military is just as eager as the civilian world to harness driverless vehicle technology for its own ends. The Department of Defense's emerging technologies arm, DARPA, has hosted a series of competitions that award big prizes to the teams that demonstrate exceptional self-driving capability.

These "Challenges" have taken place sporadically since the mid-2000s. The first one wasn't a raging success, as none of the entrants (consisting of teams of researchers) managed to complete the 142-mile route across California's Mojave Desert. The following year was a different story, with five contestants finishing the course.

The best performers were rewarded well. In the 2007 Urban Challenge, the winner claimed a $2 million prize, while the first runner-up received $1 million, and No. 3 took home $500,000.

4. One fleet of them has now logged over 1 million miles of travel distance
Arguably, the company most readily identified with the development of the autonomous car, Alphabet's Google, is laboring mightily to help transition to full autonomy.

So much so that its fleet collectively has surpassed the 1 million mile mark (in fact, that was some time ago -- as of last month the company was north of 1.4 million). And that tally includes road time not only on test sites; it also comprises forays in and around the company's home of Mountain View, California, plus Austin, Texas, and Kirkland, Washington.

For the most part, those 1 million-plus miles have been incident-free; Google has claimed that its cars were not at fault in the dozen or so accidents that have occurred over the years. However, that changed last month when a driverless Google car crashed with a bus; apparently, the car was attempting to maneuver around a set of sand bags, putting itself in the path of the oncoming vehicle.