cant say for sure, I was there 94-98 and about 90% of my driving was only on A-5, A-6 and A-8 and there always seemed to be a lot of traffic except on Sundays.
http://gettingaroundgermany.home.att.net/autobahn.htm#regsSpeed limits
Despite the widespread belief of complete freedom from speed limits (and a lobbying effort that has the same power and deep pockets as the American gun lobby), some speed regulations can be found on the Autobahns. Many sections do indeed have posted limits ranging from 80 to 120 km/h (50-75 mph), particularly those with dangerous curves, in urban areas, near major interchanges, or with unusually constant heavy traffic. In construction zones, the limit may be as low as 60 km/h (37 mph). Also, some sections now feature nighttime and wet-weather speed restrictions, and trucks are always regulated (see table below). Still, about half the Autobahn system has no speed limit, but there is always an advisory limit of 130 km/h (81 mph). This recommendation is generally seen for what it is-- an attempt by the government to cover itself without having to upset millions of Porsche and BMW owners (AKA voters.) However, if you exceed the advisory limit and are involved in an accident, you could be responsible for some of the damage costs even if you are not at fault.
Passing on the right is strictly prohibited! Slower vehicles must move to the right to allow faster traffic to pass, and drivers should stay in the right lane except to pass. When passing, you must do so as quickly as possible, and it's in your best interest to do so lest you become a hood ornament on that Porsche that was just a speck in your mirror a second ago and now is close enough for you to see the look of distain on the driver's face. You are, however, allowed to pass on the right in heavy traffic when vehicles have started queuing, but only at a slow speed.
