I’ve read your post a couple times and I can’t seem to find your question.
A few things to keep in mind when talking about driving as fast as insanely possible on the Autobahn.
First: There are speed limits on the Autobahn. Not all of it is free of speed limits. Sometimes the limits are time or weather dependant. Or possibly there is construction going on. In other places, the limits are permanent. Usually, when there is a limit, it is 120kph. So if you decide to drive as fast as you can, be prepared to decelerate from 400kph to 120kph in a relatively short distance. Can your brakes handle that without warping?
Second: Where speed limits do not exist, there can still be natural inhibitors to your speed. For instance, winding roads. Hardly anywhere on the Autoban is straight and flat. If you have little experience taking curves in that car, don’t assume the way ahead is easy driving. GPS navigation can help with this because it continuously shows you how tight the turns are coming up.
Third: Other cars will slow you down. Germany is probably the best place I have driven when it comes to other drivers obeying the rules and respecting the fast lane. But even still, if you’re driving above 350kph, you will come up on another car pretty quickly–even in the fast lane. That other car may be doing 220kph to pass a car doing 180kph, but that still isn’t fast enough to get out of your way before you’re right up on him. Again, can your brakes handle this? IMO, the Autobahn works your brakes much worse than it works your engine.