Nobody disputes that Autobahn traffic can be slow and come to a total stop, depending on various factors like location, time, weather, accidents, etc. In and around bigg cities, Autobahn traffic can be as tedious as on highly traveled roads anywhere else. There are also vast stretches of Autobahn that have generally much less traffic. I have repeatedly driven the circa 750 miles from the Austrian border to the Baltic in 7 hours at night and in the early morning. You just have to plan well and avoid trouble spots and certain times of the day. I've also gotten stuck in Autobahn traffic jams around Munich for hours without moving more than a few kilometers.
Commercial trucks over 3.51 tons must not go faster than 80 km/h. The general rule is that anyone in a passenger vehicle or truck, who wants to pass another vehicle, must be able to do so at a reasonably high speed (+20 km/h). The minimum allowed speed on the Autobahn is 60 km/h. Theoretically, no truck could ever pass another another truck unless the slower truck goes less than 60 km/h. Sure, trucks and big rigs do pass each other and cause accidents on occasion.
An Autobahn can have anywhere from 2 lanes (plus breakdown lane) to 5 or 6 lanes. Minimum distances between cars (half the driven speed in meters -- for example, at 200 km/h you must maintain 100 meters distance to the car in front of you) are pretty much enforced (photo radar traps on overpasses).
Generally speaking, this is a typical view, zipping along on winter tires at a leisurely 150 km/h on a slightly slushy two-lane Autobahn on a crappy winter day:
Picture taken in November 2004
PS: Guess the make and model.