GREETINGS FROM the back seat of the world's smartest car.

Mercedes-Benz's autonomous research vehicle—cleverly disguised as a large black sedan—has been taking this reporter on a tour of hallowed ground. In August 1888, Bertha Benz, the wife of Karl Benz, actually stole her husband's prototype motorwagen, then the only automobile in the world, and drove it from Mannheim, Germany, to her mother's house in Pforzheim, some 60 miles away. It's a whole big thing with the company...

Look! Over there! A tree! See, you have a lot of downtime in this car, because it drives itself. To be clear, it drives itself under the wary eye of at least a couple of engineers at all times, who are watching the car's autonomous-driving operation and carefully recording errors so that they can dial in software fixes back at the lab.

Eberhard Kaus, sitting in the driver's seat, is also there to grab the wheel in case the car becomes baffled by one of the route's many intersections, roundabouts, parked cars or random pedestrians crossing the street in Bruchsal's Imperial district.

At the frontier of making cars drive themselves, one big technical lift is the writing of pattern-matching algorithms so the machine brain understands what the machine vision sees. As the speed of traffic increases, these algorithms must become increasingly predictive, anticipating, as humans do, the probable intention of drivers in other vehicles.